Symposium Organizers
Prabhakar Bandaru University of California-San Diego
Morinobu Endo Shinshu University
Ian Kinloch University of Cambridge
Apparao M. Rao Clemson University
Q1:Physics and Modeling of Nanotubes and Nanowires
Session Chairs
Prabhakar Bandaru
Morinobu Endo
Ian Kinloch
Monday PM, November 27, 2006
Room 312 (Hynes)
9:00 AM - Q1.1
Atomistic Theory and Simulation of Electronic and Molecular Transport in Carbon Nanotubes.
Yongqiang Xue 1
1 College of Nanoscale Science & Engineering, University at Albany-SUNY, Albany, New York, United States
Show Abstract9:15 AM - Q1.2
Dielectric Response of Carbon and Boron Nitride Nanotubes from First-principles Calculations.
Boris Kozinsky 1 , Nicola Marzari 1
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractWe present a complete characterization of the electrostatic response of isolated single- and multi-wall carbon (CNT) and boron nitiride nanotubes (BNNT) using first-principles calculations and density-functional theory. The longitudinal polarizability of a single nanotube is sensitive to the band gap and its radius, and in multi-wall nanotubes and bundles it is trivially given by the sum of the polarizabilities of the constituent tubes. The transverse polarizability of both types of nanotubes is insensitive to band gaps and chiralities and depends only on the radius. However, the transverse response and screening properties of BNNTs are qualitatively different from those of both metallic and semiconducting CNTs. Their comparison helps to illuminate the fundamental differences of electronic interactions in the two materials, that are inherited from the corresponding two-dimensional sheets. The screening of the external field in CNTs is much stronger than in BNNTs and has a very different radius dependence. The transverse response in BNNTs is found to be that of an insulator, while in CNTs it is intermediate between metallic and semiconducting. For carbon nanotubes we construct a simple electrostatic model based on a scale-invariance relation that captures accurately the first-principles results and allows calculation of transverse response in any multi-wall CNT. Our results have practical implications for selective growth of different types of nanotubes using aligning electric fields and for Raman characterization of nanotubes.
9:30 AM - Q1.3
A First-principles Study of Pd-covered Semiconducting Carbon Nanotubes.
Wenguang Zhu 1 2 , Efthimios Kaxiras 1
1 Department of Physics and Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States, 2 Center for Computational Materials, Institute for Computational Engineering and Sciences, Departments of Physics and Chemical Engineering, University of Texas, Austin, Texas, United States
Show Abstract9:45 AM - Q1.4
Pressure Induced Transformation of Carbon Nanotubes into New Crystalline Polymerized Nanotube Phase: A Molecular Dynamics Study.
Susumu Saito 1 , Yuichiro Yamagami 1
1 Department of Physics, Tokyo Institute of Technology, Tokyo Japan
Show Abstract10:00 AM - Q1.5
Challenges in Chirality Assignment for Carbon Nanotubes.
Francesca Clemente 1 2 , Olivier Richard 1 , Thomas Hantschel 1 , Wilfried Vandervorst 1 2
1 , IMEC, Leuven Belgium, 2 , K.U.Leuven, INSYS, Leuven Belgium
Show Abstract10:15 AM - Q1.6
Band-gap Modulation and Kohn Anomalies in Two-dimensional Graphite and Single-wall Carbon Nanotubes.
Georgii Samsonidze 1 , Eduardo Barros 2 , Hyungbin Son 1 , Riichiro Saito 3 , Gene Dresselhaus 4 , Mildred Dresselhaus 1 5
1 Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Departamento de Fisica, Universidade Federal do Ceara, Fortaleza, Ceara, Brazil, 3 Department of Physics, Tohoku University and CREST JST, Sendai Japan, 4 Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 5 Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show Abstract10:30 AM - Q1.7
Thermodynamic Solubility of Carbon Nanotubes in Common Solvents.
Jonathan Coleman 1
1 School of Physics, Trinity College Dublin, Ireland Ireland
Show AbstractDispersion of single wall carbon nanotubes in a wide range of high surface tension solvents has been demonstrated. In general SWNT can be satisfactorily dispersed by sonication at concentrations in the range 0.1-1 mg/ml. These dispersions have been characterized by TEM, AFM, spectroscopy and IR photoluminescence. However, as these initial dispersions are diluted with additional sonication the SWNT bundles tend to exfoliate. This results in the decrease in the mean bundle diameter from ~10nm at CNT~0.1 mg/ml to <2nm at CNT<10-2 mg/ml. At the same time the population of individual SWNT increases from ~5% to ~80%. Detailed analysis shows that the concentration dependence of the bundle size is controlled by the presence of an equilibrium bundle number density. More interestingly, in certain special solvents such as NMP, these process occur spontaneously upon dilution, without the need for sonication. The kinetics of this process have been measured. At equilibrium, the mean bundle diameter scales with the square root of concentration again indicating the present of an equilibrium bundle number density. Interestingly this equilibrium number density is exactly that for the system to balance on the dilute-semi-dilute boundary. A model describing the enthalpy of mixing for these systems has been developed and confirmed by experiment. This allows us to understand some of the criteria required for a solvent to disperse nanotubes successfully. This model also shows that in the best solvents the enthalpy of mixing is very close to zero. This means that the free energy of mixing is negative and that the nanotubes are truly dissolved in these systems. Finally, the ability to effectively debundle nanaotubes allows us to demonstrate advanced applications such as extremely low percolation thresholds in conductive composites.
Q2: Carbon Nanostructure Growth I
Session Chairs
Prabhakar Bandaru
Ian Kinloch
Monday PM, November 27, 2006
Room 312 (Hynes)
11:15 AM - **Q2.1
Geometry-Controlled Carbon Nanotubes.
Sungho Jin 1
1 Materials Science & Engineering, University of California, San Diego, La Jolla, California, United States
Show AbstractFor successful engineering applications of carbon nanotubes and other nanowires, an ability to control their basic configurations is essential, for example, in terms of geometry manipulations and appropriate placements on a substrate. In this talk, various fabrication techniques and microstructural analyses for controlling the nanotube geometry such as diameter, length, alignment, spacing, periodicity, bending, branching, opening, cutting, shortening, and bonding will be discussed. Growth of patterned nanotubes or nanocone arrays, sharp bending of nanotubes for creation of 90o bent or zig-zag nanotubes will be discussed. Additional geometry modifications such as the removal of catalyst metal particles from aligned multiwall nanotubes for purification and uncontaminated electrochemical reactions, tip opening and filling of nanotubes for nanocomposite formation, and coating of nanotubes with high-density Pt catalyst nanoparticles will also be discussed. The implications of such geometry controls for physical, electronic, chemical, mechanical, and bio-related properties will be discussed in relation to potential technical applications such as field emission devices, sensors, nanosprings, nanosolenoids, AFM probes, fuel cell electrodes, electronic circuit nano interconnections, and nanocomposites.
11:45 AM - Q2.2
Fast and Position-Controlled Growth of Single-walled Carbon Nanotubes.
Zuqin Liu 1 , David Styers-Barnett 1 , Alex Puretzky 1 , Chris Rouleau 1 , IIia Ivanov 1 , Dongning Yuan 2 , Jie Liu 2 , David Geohegan 1
1 Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 2 Department of Chemistry, Duke University, Durham, North Carolina, United States
Show Abstract12:00 PM - Q2.3
Combinatorial Development of Catalysts for CVD Synthesis of Carbon Nanotubes.
Benjamin Hertzberg 1 , Jonathan Petrie 1 , R. van Dover 1
1 Materials Sci. & Eng, Cornell University, Ithaca, New York, United States
Show Abstract12:15 PM - Q2.4
Dynamic Restructuring Of Solid Catalyst Cluster During Carbon Nanotube CVD.
Stephan Hofmann 1 , Renu Sharma 2 , Gaohui Du 2 , Mirco Cantoro 1 , Simone Pisana 1 , Atlus Parvez 1 , Caterina Ducati 3 , Rafal Dunin-Borkowski 3 , John Robertson 1
1 Engineering, University of Cambridge, Cambridge United Kingdom, 2 Center for Solid State Science, Arizona State University, Tempe, Arizona, United States, 3 Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom
Show Abstract12:30 PM - Q2.5
In-Situ Studies of Single-Walled Carbon Nanotubes Growth Under Reductive and Oxidative Ambient.
Avetik Harutyunyan 1 , Elena Mora 1
1 Material Science, Honda Research Institute USA Inc., Columbus, Ohio, United States
Show AbstractQ3: Carbon Nanostructure Growth II
Session Chairs
Prabhakar Bandaru
Ian Kinloch
Monday PM, November 27, 2006
Room 312 (Hynes)
2:30 PM - Q3.1
Controlling the Catalyst Shape and Size Controls Nanotube Growth.
John Robertson 1 , Stephan Hofmann 1 , Mirco Cantoro 1 , Simone Pisana 1 , Atlus Parvez 1 , Andrea Ferrari 1 , Caterina Ducati 1
1 Engineering, Cambridge University, Cambridge United Kingdom
Show Abstract2:45 PM - Q3.2
Catalyst-Free Growth of Carbon Nanotubes on Nonplanar, Porous, Polycrystalline Silicon Carbide Substrates for Electrochemical and Photochemical Applications.
Elmo Blubaugh 1 , Heidi Cross 1 , Mike Check 1 , Bill Riehl 1
1 R&D, Riehl-Check Industries, LLC., Kettering, Ohio, United States
Show Abstract3:00 PM - **Q3.3
Tuning Structure and Function of Carbon Nanofiber and Metal Nanoparticles in a Controlled Co-synthesis Process.
Anatoli Melechko 1 , Kate Klein 1 2 , Jason Fowlkes 1 2 , Philip Rack 2 , Michael Simpson 1 2
1 Molecular-Scale Engineering and Nanoscale Technologies, Oak Ridge National Lab, Oak Ridge, Tennessee, United States, 2 Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee, United States
Show AbstractQ4: Carbon Nanostructure Growth III
Session Chairs
Prabhakar Bandaru
Ian Kinloch
Monday PM, November 27, 2006
Room 312 (Hynes)
4:30 PM - **Q4.1
Controlled Assembly of Carbon Nanotube Architectures.
Pulickel Ajayan 1
1 Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States
Show Abstract5:00 PM - Q4.2
The Growth and Properties of Highly Crystalline Multi-walled Carbon Nanotubes.
Krzysztof Koziol 1 , Caterina Ducati 1 , Steffi Friedrichs 2 , Milo Shaffer 3 , Paul Midgley 1 , Alan Windle 1
1 Department of Materials Science, University of Cambridge, Cambridge United Kingdom, 2 , The Technology Partnership plc, Royston United Kingdom, 3 Department of Chemistry, Imperial College Science Technology & Medicine, London United Kingdom
Show Abstract5:15 PM - Q4.3
High Uniformity Growth of Sub-Nanometer (0.7 nm) Diameter Single-Walled Carbon Nanotubes using Catalyst Particle Templates Produced by Nanosphere Lithography.
Noureddine Tayebi 1 2 , Joseph Lyding 1 2
1 Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show Abstract5:30 PM - Q4.4
Vertically Aligned Carbon Nanotube Growth with Uniform Diameter Distribution by Block Copolymer Micellar Catalyst Templates.
Xi Liu 1 , Terry Bigioni 1 , Alan Cassell 1 , Brett Cruden 1
1 , NASA Ames Research Center, Mountain View, California, United States
Show Abstract5:45 PM - Q4.5
Growth and In-Situ Optical Characterization of Aligned Carbon Nanotube Monoliths Using a Desktop Reactor Apparatus with Rapid Thermal Control.
Lucas van Laake 1 2 , A. Hart 1 , Don Lucca 3 , Lin Shao 4 , Matt Klopfstein 3 , Alexander Slocum 1
1 Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Mechanical Engineering, Eindhoven University of Technology, Eindhoven Netherlands, 3 School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, Oklahoma, United States, 4 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show AbstractWe present studies of growth of thick films (monoliths) of aligned carbon nanotubes (CNTs), along with in-situ optical characterization of the growth reaction and ex-situ studies of the catalyst evolution by Rutherford Backscattering Spectrometry (RBS). Growth is performed using a novel desktop reactor apparatus, based on resistive heating of a freely suspended p++ silicon substrate. The substrate is cut from a 6” wafer and clamped between steel blocks, which make electrical contact and mechanically support the substrate, and the assembly is sealed in a quartz enclosure. Due to its unique suspended configuration, the substrate can be heated and cooled rapidly at 100°C/s, using a conventional laboratory power supply (25 V, 4 A). With this, we can study growth of nanostructures under parameter variations that are not achievable in classical tube furnaces; for example, we study the effect of rapid temperature oscillations and thermally “pulse” growth using very short reaction times. We also optically image the film during growth and thereby measure the time evolution of the thickness and topography.Specifically, by heating a catalyst-coated growth substrate (1.2/10nm Fe/Al2O3 on Si [1]) to 800°C, while separately pre-activating the reaction gases (C2H4/H2/CO) by quickly heating to 1100°C followed by subsequent cooling before reaching the substrate, we rapidly grow monoliths of aligned multi-wall CNTs (MWNTs) to over 3 mm thickness in just 20 minutes. In-situ optical measurement of the film thickness reveals an essentially constant growth rate during this period. The method of decoupling the thermal pre-treatment of the reaction gases from the substrate temperature enables optimal generation of active carbon species for CNT growth, which significantly boosts the growth rate. Combining the in-situ measurement results with RBS measurements of the substrate surface after delaminating the CNT film, we compare effects of catalyst migration and reactant diffusion limitation on the terminal film thickness. Further, in-situ imaging from the top view reveals crack-formation in the film during growth, newly demonstrating the significance of mechanical stresses arising from spatial non-uniformities in the growth rate. We have separately shown that applying vertically-compressive stress during growth can generate severe defects in MWNTs [2].By a different choice of catalyst and gas composition (3/1.5/20nm Mo/Fe/Al2O3, CH4/H2 [3]) we also grow high-quality films of tangled SWNTs using this system.In an aluminum enclosure we make secondary electrical contact to substrates or microsystems placed on the heated substrate, enabling direct growth and in-situ electrical testing of CNTs on microelectronic and micromechanical devices.[1] A.J. Hart, A.H. Slocum, J. Phys. Chem. B, 110:8250-7, 2006.[2] A.J. Hart, A.H. Slocum, Nano Letters, 6:1254-60, 2006.[3] A.J. Hart, A.H. Slocum, L. Royer, Carbon, 44:348-59, 2006.
Q5: Poster Session: Nanotubes and Nanowires: Growth and Assembly
Session Chairs
Prabhakar Bandaru
Morinobu Endo
Ian Kinloch
Apparao Rao
Tuesday AM, November 28, 2006
Exhibition Hall D (Hynes)
9:00 PM - Q5.1
Lower-pressure Effects on Single-wall Ccarbon Nanotubes Growth in Alcohol Catalytic Chemical Vapor Deposition.
Takao Shiokawa 1 2 , Hiroshi Yoshida 1 3 , Bao-Ping Zhang 4 , Masaki Suzuki 1 2 , Koji Ishibashi 1 2
1 Advanced Device Laboratory, RIKEN, Wako, Sitama, Japan, 2 , CREST-JST, Kawaguchi, Saitama, Japan, 3 , Tokyo University of Science, Shinjyuku, Tokyo, Japan, 4 , Xiamen University, Xiamen, Fujian, China
Show AbstractThe low-pressure growth of single-wall carbon nanotubes (SWNTs) is attractive in terms of an expected precise growth control and a necessary low-temperature growth to realize the SWNTs based nanodevices combined with a two-dimensional GaAs/AlGaAs system[1]. In this paper, we will describe the successful growth of SWNTs at the low pressure down to 0.02Pa in an ultra high vacuum (UHV) chamber, using the alcohol catalytic chemical vapor deposition (ACCVD) with Co catalysts.A sample of Co(0.1nm)/ SiO2/Si was prepared for the substrate. In the low-pressure growth at 0.02Pa, the growth temperature was varied from 550°C to 900 °C with growth time of 500 min. The base pressure before introduction of ethanol was less than 1.0 x10-6 Pa. To investigate the low-pressure effects, SWNTs were grown also with the standard conditions of the pressure of 1.5 kPa and the growth time of 5 min, using the conventional ACCVD system and the same sample. The sample surface was observed with the field-emission scanning electron microscope (FE-SEM), Raman spectra were measured by the argon-ion laser with a wavelength of 514.5 nm.In the samples grown at 0.02 Pa, peaks of the radial breathing mode (RBM) and the splitting of the G-band peak are observed, indicating the existence of SWNTs on the substrate. In our knowledge, 0.02 Pa of the ethanol gas pressure is the lowest one ever tried for the CVD growth. The maximum intensity of the G+ signal was obtained at 550 °C for 0.02Pa, while it was obtained at 850 °C for 1.5 kPa, suggesting that the optimum temperature was reduced with ~300 °C by decreasing the pressure from 1.5 kPa to 0.02 Pa. It is interesting to mention that the RBM spectra of 0.02 Pa measured in the sample with the maximum G+ intensity was similar to that of 1.5kPa, although the two conditions are very different, meaning that the diameter distribution of SWNTs is also similar. This result suggests that it may be defined dominantly by the size distribution of the catalyst. More detailed results will be presented.[1] T. Shiokawa et al., Jpn.J.Appl.Phys., Part 2 45,L605(2006).
9:00 PM - Q5.10
Diameter and Metallicity Dependent Dedoping and Separation of Single Wall Carbon Nanotubes.
Steve Kim 1 , Zhengtang Luo 1 , Fotios Papadimitrakopoulos 1
1 Polymer Program, IMS, University of Connecticut, Storrs, Connecticut, United States
Show Abstract9:00 PM - Q5.11
Single Wall Carbon Nanotube (SWNT) Production in a Vertical Furnace by the Floating Catalyst Method.
Ranadeep Bhowmick 1 2 , Brett Cruden 2 , Bruce Clemens 1
1 Materials Sc & Engg, Stanford University, Stanford, California, United States, 2 Center for nanotechnology, NASA Ames Research Center, Moffett Field, California, United States
Show Abstract9:00 PM - Q5.12
A New Laser-heated CVD Setup for Studies of Local Carbon Nanotube Growth.
Lucas van Laake 1 , Yves Bellouard 1 , Andreas Dietzel 1
1 Mechanical Engineering, Eindhoven University of Technology, Eindhoven Netherlands
Show AbstractWe report on a new setup for laser-assisted chemical vapor deposition of carbon nanotubes. The basic concept is to use a focused laser beam to locally heat a catalyst layer deposited on a substrate in order to thermally induce nanotube growth. The objective is to introduce nanotubes at selected locations on delicate substrates or to form arbitrary patterns without the need to pre-pattern the catalyst layer. We use two different substrate materials: Si with a SiO2 layer and fused silica. A CW-CO2 laser beam is radiated from the bottom; as silicon is partially transparent at the laser wavelength (10.6μm), most of the energy directly couples to the oxide intermediate layer resulting in local heating of the catalyst. In the case of fused silica, as the material is opaque at 10.6μm, the energy is directly absorbed in the first tenths of microns of the substrate thickness. Specimens are placed inside a vacuum chamber where pressure and gas composition are independently controlled: Gas composition and total mass flow of the reactant mixture are controlled by mass flow controllers and pressure is set by a variable leak valve between chamber and vacuum pump. Pressure ranges between low vacuum (10-3mbar) and twice atmospheric pressure (2000 mbar). A custom-designed self-aligning substrate holder ensures repeatable substrate placement and an integrated gas delivery unit provides repeatable gas supply even at higher flow rates and pressures.Two viewports are provided to illuminate and observe the growth site from the top. Since the heating laser enters from the bottom, it does not interfere with measurements on the top surface. CNT growth is studied in-situ using various optical methods including reflectivity measurements. The effect of substrate temperature distribution, gas composition, pressure and flow-rate are investigated.
9:00 PM - Q5.13
Contrast Imaging of Carbon Nanofiber-Substrate Interface using Scanning Electron Microscopy.
Makoto Suzuki 1 , Yusuke Ominami 1 , Quoc Ngo 1 2 , Toshishige Yamada 2 , Alan Cassell 2 , Jun Li 2 , Cary Yang 1
1 Center for Nanostructures, Santa Clara University, San Jose, California, United States, 2 Center for Nanotechnology, NASA Ames Research Center, Moffett Field, California, United States
Show AbstractAlthough nanoscale materials have been extensively studied for their applications in high performance electronics, there still exists a critical issue of the controllability of their precise positioning for higher production yield. Recent studies reveal that the thermal and electrical properties of one-dimensional materials such as carbon nanotubes and carbon nanofibers (CNFs) strongly depend on their configuration, especially thermal dissipation via the support material on which they rest. The extent to which the nanofiber is in contact with the support material (or substrate) determines how heat is transported within the entire structure. Thus investigation of the CNF-substrate interface is essential for achieving stability and reliability of any potential CNF device.We present a rapid imaging technique to study the interface nanostructures between CNFs and substrate using scanning electron microscopy (SEM). In our experiment, CNFs grown by plasma-enhanced chemical vapor deposition (PECVD) are dispersed onto a silicon substrate. Because as-grown CNFs are not completely straight, some of them are placed with only part of their sidewalls in contact with the substrate. This partial contiguity between nanofiber and substrate can adversely affect heat dissipation. We perform SEM imaging of these CNFs with diameters ranging from 250 nm down to 25 nm by irradiating the electron beam perpendicular to the substrate. We found that, by using electron beam energy higher than a particular threshold, the SEM image of CNFs exhibits different contrasts depending on whether or not the irradiated part of the CNF is in contact with the substrate. The threshold energy is found to be close to the energy required to penetrate the CNFs, thus the contrast mechanism observed here can be explained by modeling electron penetration into a solid and considering the edge effect of SEM image formation. With this contrast mechanism, the interface nanostructures can be imaged very rapidly without substrate tilting, which can deteriorate image resolution due to the large working distance and can degrade the imaging efficiency due to the small in-focus area within the scanning field of the electron beam. This technique can also be applied to imaging other similar structures such as nanowires resting on support materials.
9:00 PM - Q5.14
The Effect of Catalyst Composition on the Growth of Carbon Single-Walled Nanotubes.
Elena Mora 1 , Toshio Tokune 1 , Avetik Harutyunyan 1
1 , Honda Research Institute USA Inc., Columbus, Ohio, United States
Show AbstractThe growing interest to use carbon single-walled nanotubes (SWNTs) in different applications demands a reasonably pure and homogeneous (diameter, chirality) material. To achieve this, a full understanding of the effect of the catalyst composition and the synthesis parameters on the growth of the tubes should be acquired. It is well known that the addition of small amounts of certain additives to the metal catalyst significantly improves the SWNT yield when using chemical vapor deposition (CVD) method. In this work, the performance of Fe/Mo/Al2O3 and Fe/Al2O3 catalysts are compared, in order to study the effect of the different composition in the growth of carbon single-walled nanotubes (SWNTs). The use of a Mass Spectrometer attached to the outlet of the CVD apparatus allowed us to study, in situ, the effect on both catalyst activity and lifetime during the growth of SWNTs, by following the hydrogen formed in the decomposition of the hydrocarbon (CH4). We observed that Mo not only improves the Fe catalyst activity and lifetime, but also decreases the activation energy for decomposition of the hydrocarbon (over 350 οC relative to the thermal case). As a result, the growth initiates earlier and is prolonged for longer times resulting in higher SWNTs yields compared to the monometallic catalyst. The results are in agreement with independent experiments to study the evolution of the Raman spectra with both temperature and synthesis time, as well as the evolution of the carbon up-take. In addition, experiments performed using sequential introduction of 12CH4 and 13CH4 not only confirmed the longer catalyst activity for SWNTs growth of the bimetallic catalyst, but also revealed that the poisoning of the catalysts occurs through different mechanism after the addition of Mo. The results obtained in this work also point to a substantial intermetallic interaction between Mo and Fe with possible formation of Fe-Mo alloy, in this manner protecting the solidification of the catalyst due to the formation of stable carbide phases and prolonging the catalyst lifetime.
9:00 PM - Q5.15
Synthesis and Structure of Carbon Nanotube Y-junctions.
Bimal Pandey 1 , Wenzhi Li 1
1 Physics, Florida International University, Miami, Florida, United States
Show AbstractThe effect of catalysts on the growth and structure of carbon nanotube Y-junctions (CNTYs) has been investigated by using three different nitrates (i.e. cobalt-, magnesium-, and calcium-nitrates) and their mixtures as catalyst precursors. CNTYs with straight branches have been synthesized by using mixture of cobalt nitrate/magnesium nitrate or cobalt nitrate/calcium nitrate with different concentrations. Pure cobalt nitrate, magnesium nitrate, and calcium nitrate, or mixture of magnesium nitrate and calcium nitrate will not grow any CNTYs, indicating that only binary catalysts Co/Mg and Co/Ca will facilitate the formation of CNTYs. In addition, the effect of carbon sources on the formation of CNTYs has also been studied. It is found that thiophene (C4H4S) can promote the formation of CNTYs; other sources such as methane (CH4) and acetylene (C2H2) can grow linear CNTs rather than branched Y-junctions. This result shows that sulfur is playing an important role in the formation of CNTYs. Structure examination indicates that the angles between the branches of CNTYs are about 80°, 135°, and 145°, showing fractal growth feature.
9:00 PM - Q5.16
Direct Evidence for base-growth Through Aligned Multi-walled Carbon Nanotube Multilayers.
Mathieu Pinault 1 2 , Martine Mayne-L’Hermite 2 , Cecile Reynaud 2 , Vincent Pichot 3 , Pascale Launois 3 , Hicham Khodja 4
1 Chemical Engineering, Yale University, New Haven, Connecticut, United States, 2 Laboratoire Francis Perrin (URA CNRS 2453), CEA Saclay DSM-DRECAM-SPAM, Gif sur Yvette France, 3 Laboratoire de Physique des Solides (UMR CNRS 8502), Université Paris Sud, Orsay France, 4 Laboratoire Pierre Süe, UMR 9956, CEA Saclay, Gif sur Yvette France
Show Abstract9:00 PM - Q5.17
Isolated Bundles of High Quality, Highly Uniform Single Wall Nanotubes Grown at very Low Substrate Temperature.
Sakthi Kumar 1 2 , Yasuhiko Yoshida 1
1 Bio Nano Electronics Research Center, Toyo University, Kawagoe-shi, Saitama, Japan, 2 REDS Group/JST, Saitama Small Enterprise Promotion Corporation, SKIP City, Kawaguchi, Saitama, Japan
Show Abstract9:00 PM - Q5.18
Growth of Horizontally Aligned Carbon Nanotubes: A Systematic Study of Growth Mechanisms.
Alfonso Reina 1 , Jing Kong 2
1 Materials Science, MIT, Cambridge, Massachusetts, United States, 2 Electrical Engineering and Computer Sciences, MIT, Cambridge, Massachusetts, United States
Show AbstractCarbon nanotubes (CNTs) are considered excellent candidates for interconnect applications due to their high current carrying capability, low resistance and high mechanical stability. Theoretical studies have compared the performances of current copper interconnects and interconnects made of individual CNTs connected in parallel or CNT bundles. These studies predict a significant enhancement of interconnect performance at the 22 nm node if CNTs are implemented. Also, extensive work has been done to build and test prototypes of CNT-based transistors and electronic devices. However, their reliable synthesis and integration for modern circuits remains a challenge. It is still necessary to have further control over CNT location, orientation and density to build required device architectures. The simultaneous synthesis and horizontal alignment of single-walled carbon nanotubes (SWNTs) on a substrate using the gas flow inside a CVD chamber has been demonstrated, but the mechanism is not yet well understood and the results have encountered non-reproducibility issues. Here, a systematic study of gas flow-assisted synthesis of long and horizontally aligned CNTs from iron-based catalyst nanoparticles on SiO2/Si substrates is presented. From the vast number of process variables, the most critical ones needed to obtain alignment of CNTs with the gas flow are underlined and their effect on the final result discussed. It is found that not only the drag of the gas flow or its non-turbulent nature is necessary for alignment but also catalyst preparation, treatment and in-situ chemical changes are extremely important. Finally, these experimental observations are helpful to understand both chemical and physical mechanisms of the growth of short (few microns) and long (hundreds of microns to centimeters) CNTs from catalyst nanoparticles on SiO2/Si substrates.
9:00 PM - Q5.19
Controlling the Morphology of Carbon Nanotube Films by Varying the Areal Density of Catalyst Nanoclusters Using Block Copolymer Micellar Thin Films.
Ryan Bennett 1 , Anastasios Hart 2 , Robert Cohen 1
1 Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractWe demonstrate a general route that utilizes block copolymer micelles as a means to create tunable inorganic nanocluster arrays which serve as catalysts for carbon nanotube (CNT) growth. Our approach uses the amphiphilic block copolymer, poly(styrene-block-acrylic acid) (PS-b-PAA), which forms spherical micelles in solution that can be selectively loaded with metal ions and then spin-coated onto a substrate to create quasi-hexagonal arrays of metal-loaded PAA domains within a PS matrix. This catalyst system has significant value compared to commonly prepared thin metal film catalysts because it enables the creation of nanocluster arrays of a chosen metal species, with independent control of the nanocluster diameter and areal density. We use this block copolymer micellar system to create iron oxide nanoclusters, which are catalytically active in the thermal chemical vapor deposition (CVD) growth of CNTs. Through appropriate selection of the substrate, catalyst preparation procedure, and reaction conditions (combination of C2H4/H2/Ar gases), we achieve vertical CNT growth from our catalyst system. Because this catalyst system allows for precise quantification of the nanocluster areal density, we can also estimate the percentage of nanoclusters which nucleate the growth of a CNT. By uniformly varying the areal density of iron oxide nanoclusters on the substrate surface, we manipulate the morphology of the CNT film from a tangled and sparse arrangement of individual CNTs, through a transition region with locally bunched and self-aligned CNTs, to rapid growth of thick vertical CNT films. We also present a microcontact printing approach to create patterned inorganic nanocluster arrays that are utilized to synthesize patterned vertical growth of CNTs. The control afforded by this micellar catalyst system could be promising for both CNT applications as well as for improved understanding of the combination of chemical and mechanical conditions necessary for the growth of uniform CNT films.
9:00 PM - Q5.2
Control of The Growth Rate of Carbon Nanotubes by Ion Fluxes in CH4/H2 Plasma.
Atsushi Okita 1 , Yoshiyuki Suda 1 , Atsushi Ozeki 1 , Junji Nakamura 2 , Akinori Oda 3 , Krishnendu Bhattacharyya 1 , Hirotake Sugawara 1 , Yosuke Sakai 1
1 Graduate School of Information Science and Technology, Hokkaido University, Sapporo Japan, 2 Institute of Materials Science, University of Tsukuba, Tsukuba Japan, 3 Graduate School of Engineering, Nagoya Institute of Technology, Nagoya Japan
Show AbstractApplications of carbon nanotube (CNT) to LSI require a precise control of CNT growth in terms of the length, diameter, number density, and quality. The goal of this study is to achieve the CNT growth with a high controllability for the applications. We have attempted control of the growth rate of CNTs using plasma-enhanced chemical vapor deposition (PECVD). An advantage of PECVD is effective production of active species (radicals and ions). We believe that the growth rate of CNT is controllable via the supply of these active species. So far, we have studied the CH4 and CH4/H2 plasmas and grown CNTs to analyze the correlation between species produced in the plasmas and catalyst surface on substrate [1-3]. Utilizing these results, we control the growth rate of CNT through fluxes of ions containing carbon atoms. We have performed CNT growth by a CH4/H2 RF plasma. To analyze the ion fluxes in CH4/H2 RF plasma, we have quantitatively simulated its plasma using 1-dimensional fluid model [1]. The PECVD setup and experimental procedure are described in the previous reports [1-3]. In this experiment, we kept total gas pressure at 10 Torr and the substrate temperature at 650oC. We used triple layered catalysts (Al2O3/Fe/Al2O3/ = 1/1/1 nm) on SiO2/Si substrates for the CNT growth. To control the ion fluxes onto the catalyst, we applied positive bias voltage to the substrate. Using a scanning electron microscope and a transmission electron microscope, we evaluated the CNT length, diameter and number density. We also investigated the effect of bias voltage using computer simulation of the CH4/H2 plasma. The amount of carbon atoms supplied as ion fluxes onto the substrate were calculated. In our experimental results, the CNT length became shorter when we applied higher positive bias voltages. The growth rate of CNT ranged from 0.15 to 0.5 μm/min depending on the bias voltage. We consider that the higher positive bias voltage prevents supply of ions onto the substrate. In the simulation results, the carbon amount supplied as ions decreased with increasing bias voltage. This simulation result agreed well with experimental one. We conclude that ions are the main precursor for CNT growth in our experiment. Controlling the bias voltage enables us to progress or to suppress the growth rate of CNT. [1] A. Okita, J. Appl. Phys. 99, 014302 (2006) [2] A. Okita, Jpn. J. Appl. Phys. (2006) in press [3] A. Ozeki, MRS Symposium Proceedings Vol. 901E 0901-Rb24-03 (2006)
9:00 PM - Q5.20
Tubulization Mechanism of Amorphous Carbon-nanopillar.
Toshinari Ichihashi 1 3 , Masahiko Ishida 1 3 , Jun-ichi Fujita 2 3
1 Fundamental & Environmental Research Laboratories, NEC Corporation, Tsukuba Japan, 3 , CREST-JST, Kawaguchi Japan, 2 Institute of Applied Physics, University of Tsukuba, Tsukuba Japan
Show Abstract9:00 PM - Q5.21
Catalyst Patterning and Location Controlled Growth of Single-Walled Carbon Nanotubes.
Ruth Zhang 1 , John Tresek 1 , Islamshah Amlani 1 , Kevin Nordquist 1 , Donald Weston 1 , Ray Tsui 1 , Larry Nagahara 1
1 Embedded Systems Research, Motorola Labs, Tempe, Arizona, United States
Show AbstractChemical vapor deposition (CVD) is a well recognized approach for location controlled formation of carbon nanotubes (CNTs) directly on substrates. Selective area growth of CNTs in this case usually involves a lithographic step to pattern catalyst materials at predetermined locations on a substrate prior to the CVD process. For the growth of single-walled carbon nanotubes (SWNTs), a layer of transition metal with thickness on the order of 1 nm or less is commonly used as the catalyst. And in some cases, another thin (a few nm) metal or insulating layer beneath the catalyst layer is required to serve as a diffusion barrier and/or catalyst support to prevent the catalyst from agglomerating into large particles during the heating process. Patterning these thin layers to successfully achieve the selective growth of SWNTs is challenging because the catalyst layer can easily be poisoned by solvent and/or resist residuals. In this paper we studied effects of the patterning process on the growth of SWNTs on oxidized Si wafers in a thermal CVD process using various catalyst materials. SWNT yield was analyzed using low voltage field emission scanning electron microscopy, and using electrical measurements after contact fabrication. We compared SWNT growth from a blanket layer of as-deposited catalyst with that from catalyst patterns defined by lift-off and by a plasma etch process. We observed a lower SWNT density and less reproducibility on wafers patterned by lift-off when compared to wafers with the corresponding blanket catalyst film. On the other hand, no density reduction is observed on wafers with catalyst patterns defined by the plasma etch process. We believe that the improved SWNT growth from etched patterns is because the catalyst is deposited on a pristine SiO2 surface while it is difficult to consistently create SiO2 windows with a clean surface using a lift-off process prior to catalyst deposition. Residual contamination can potentially poison the catalyst and hinder the formation of SWNTs.
9:00 PM - Q5.22
Synthesis of Very Dense and Vertically Aligned Carbon Nanotubes by Radical CVD.
Tsuyoshi Yoshida 1 , Daisuke Yokoyama 1 , Takayuki Iwasaki 1 , Hiroshi Kawarada 1
1 , School of Science and Engineering, Waseda University, Tokyo Japan
Show Abstract9:00 PM - Q5.23
Determination of the Chiral Indices of Carbon Nanotubes.
Lu-Chang Qin 1 , Zejian Liu 1 , Qi Zhang 1 , Gongpu Zhao 1 , Hakan Deniz 1 , Jie Tang 2 1
1 Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States, 2 Material Physics Division, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
Show Abstract9:00 PM - Q5.24
Influence of Substrate Morphology and Catalyst-substrate Interaction on Single and Multi-wall Carbon Nanotube Growth Characteristics.
Ageeth Bol 1 , Joseph Spagnola 1 2 , Christopher Murray 1
1 TJ Watson Research Center, IBM, Yorktown Heigths, New York, United States, 2 Materials Science & Engineering, North Carolina State University, Raleigh, North Carolina, United States
Show Abstract9:00 PM - Q5.25
Synthesis of Large Uniform Arrays of Mono-metallic and Bi-metallic Nanoparticles as Catalysts for SWNTs.
Sreekar Bhaviripudi 1 , Alfonso Reina 1 , Jifa Qi 1 , Jing Kong 2 , Angela Belcher 1 3
1 Materials science and Engineering, MIT, Cambridge, Massachusetts, United States, 2 Department of Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts, United States, 3 Biological Engineering Division, MIT, Cambridge, Massachusetts, United States
Show Abstract9:00 PM - Q5.27
Growth of Carbon Nanocoils in Alcohol Chemical Vapor Deposition.
Toshio Ogino 1 , Noriaki Tsuchiya 1
1 Dept. of Electrical and Computer Engineering, Yokohama National University, Yokohama Japan
Show Abstract9:00 PM - Q5.28
SWCNTs for C82 Peapods: Synthesis using Nonmagnetic Catalysts.
Miroslav Haluska 1 , M. Hulman 2 , J. Cech 1 , V. Skakalova 1 , B. Hornbostel 1 , S. Roth 1
1 von Klitzing, FKF-MPI, Stuttgart Germany, 2 Institute for Material physics , Faculty of Physics, Vienna Austria
Show Abstract9:00 PM - Q5.29
Synthesis and Characterization of Water-Soluble Phospholipid-Modified Multiwalled Carbon Nanotubes.
Peng He 1
1 Chemistry, North Carolina State University, Raleigh, North Carolina, United States
Show Abstract9:00 PM - Q5.3
Continuous Growth of CNT Forests using Bimetallic Nanoparticles.
Amandeep Sra 1 , Fabian Reyes 1 , Lawrence Overzet 1 , Gil Lee 1 , Duck Yang 2
1 Department of Electrical Engineering, The University of Texas at Dallas, Richardson, Texas, United States, 2 Department of Chemistry, The University of Texas at Dallas, Richardson, Texas, United States
Show Abstract9:00 PM - Q5.30
Systematic Investigation of Electrodeposition Process for Synthesis of Nanowires inside Nanoporous Templates.
Adam Friedman 1 , Latika Menon 1
1 Physics, Northeastern University, Boston, Massachusetts, United States
Show Abstract9:00 PM - Q5.31
HRTEM and EELS Analysis of the Functionalized Carbon Nanotubes.
Jiri Cech 1 , Martin Kalbac 2 3 , Donghui Zhang 4 5 , Lothar Dunsch 3 , Seamus Curran 5 , Siegmar Roth 1
1 Synthetic Nanostructures, Max Planck Institute For Solid State Research, Stuttgart Germany, 2 , J. Heyrovsky Institute of Physical Chemistry, Prague Czech Republic, 3 , IFW, Dresden Germany, 4 Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico, United States, 5 Department of Physics, New Mexico State University, Las Cruces, New Mexico, United States
Show Abstract9:00 PM - Q5.32
Theoretical Analysis of Non-Catalytic Growth of Nanorods on a Substrate.
S. Joon Kwon 1 , Jae-Gwan Park 1
1 Materials Science and Technology Division, Korea Institute of Science and Technology, Seoul Korea (the Republic of)
Show AbstractA theoretical analysis explaining the whole process of growth of nanorods on a substrate without a catalyst is presented. Prior to the growth of the nanorods, the reaction precursors form nuclei on the substrate. The nuclei undergo cluster migration caused by the surface diffusion of adatoms on the substrate, and this migration continues until the mean free time of the adatoms is larger than surface diffusion time. The most probable mechanism by which cluster migration takes place is the one that leads to the minimization of the cluster free energy, namely the migration of six adatoms into one fixed adatom. This cluster migration continues during several (typically smaller than 6) consecutive nuclei growth steps. After the process of cluster migration comes to an end, the nuclei grow in an isotropic manner by collection of the adatoms, until the nucleus reaches the thermodynamic size limit. The one-dimensional growth of nanorods on the nuclei which is associated with the critical radius begins when the reactant dose is smaller than a certain value, which is determined by the thermodynamic size limit and mass transport parameter. The mass transport of the reaction precursors leads to the expansion of the radius and elongation of the height of the nanorods, and the growth rate of the height is greater than that of the radius. This difference in the growth rate causes the aspect ratio to increase with increasing growth time. By comparing the experimental data in the literature (ZnO nanorods), the presented analysis explains well the non-catalytic growth of nanorods on a substrate.
9:00 PM - Q5.33
Bundle Dissociation of Single-Walled Carbon Nanotubes in Amide Solvents.
Shane Bergin 1 , Silvia Giordani 1 , Valeria Nicolosi 1 , Werner Blau 1 , Jonathan Coleman 1
1 Physics, Trinity College Dublin, Dublin , Leinster, Ireland
Show AbstractThe implementation of single-walled carbon nanotubes (SWNTs) into a wide array of applications is hindered by the formation of bundles. Many methods have been suggested to de-bundle the SWNTs, including both covalent functionalisation and non-covalent funtionalisation with surfactants, polymers and macromolecules. These methods have their advantages but the ideal situation must be to dissolve and de-bundle the SWNTs in an appropriate solvent at concentrations that are useful for their implementation in applications. In this work, we outline the physical process underlying the de-bundling of the SWNTs in the amide solvent N-methyl pyrrolidone (NMP). This is shown by an extensive atomic force microscopy study of the dispersed SWNTs over a range of concentrations, showing the SWNTs to de-bundle as a function of concentration. Similarly, the photoluminescence of the dispersed SWNTs was measured and indicated the presence of a large population of individual SWNTs. A host of other solvents, that have differing dispersive effects on SWNTs, and an explaination of the physical process underlying their varying dispersive abilities are suggested.
9:00 PM - Q5.34
Tailoring Dispersion and Microstructure of Carbon Nanotubes Using Weak Polyelectrolytes.
Jaime Grunlan 1 3 2 , Lei Liu 3 2
1 Mechanical Engineering, Texas A&M University, College Station, Texas, United States, 3 Materials Science and Engineering, Texas A&M University, College Station, Texas, United States, 2 Polymer Technology Center, Texas A&M University, College Station, Texas, United States
Show Abstract9:00 PM - Q5.35
Fabrication of Carbon Nanotube Monolayer Film at the Liquid-liquid Interface.
Jun Matsui 1 , Kohei Yamamoto 1 , Nobuhiro Inokuma 1 , Hironori Orikasa 1 , Takashi Kyotani 1 , Tokuji Miyashita 1
1 Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, Japan
Show AbstractCarbon nanotubes (CNTs) represent an important group of nanomaterials with attractive electronic, chemical, and mechanical properties. Several kinds of electric devices, such as chemical sensors, biological sensors, field-effect transistors (FET) and transparent conductive film based on the unique electric properties of the carbon nanotubes have been reported. Implementation of CNTs for these applications requires methods to fabricate carbon-nanotube ultrathin film. Moreover, carbon-nanotube ultrathin film is important for understanding its basic electrical and optical properties. Here, we report fabrication of CNT monolayer using the liquid/liquid interface. A water-dispersible carbon-nanotube synthesized using alumina template was used to fabricate CNT monolayer. To fabricate a CNT monolayer at the liquid-liquid interface the CNT aqueous solution was place into a vessel and toluene was added to the vessel. The vessel was then sonicated 20 min to create dispersion. The oil/water dispersion was stood for 1 days to form the liquid-liquid interface. Careful observation after sonication reveals that a black film is formed at the toluene-water interface. A silicon substrate was dipped vertically into the interface to transfer the assembled film formed at the toluene-water interface onto the solid substrate. Deposition method is the same as the Langmuir-Blodgett technique. The silicon substrate was washed with O3 treatment and made hydrophilic before the dipping process. The substrate was dipped into the interface at the rate of 10 mm/min and withdrawn at the same rate. The deposited film was observed by atomic force microscopy. The AFM image indicates that a densely packed CNT thin film is transferred onto the silicon substrate. Moreover, analysis of the height profile of the small area AFM image (indicated that the height of each CNT of the transferred film was determined as 17–20 nm, which is similar to the diameter of the template nanochannels, indicating that the assembled film that is formed at the liquid-liquid interface is an CNT monolayer and that the monolayer is transferable onto the silicon substrate using LB technique.
9:00 PM - Q5.36
Liquid-crystalline Processing of Oriented Carbon Nanotube Array for the Application as Thin Film Transistors.
Hyunhyub Ko 1 2 , Vladimir Tsukruk 1 2
1 Materials Science and Engineering, Iowa State University, Ames, Iowa, United States, 2 Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractWe introduce a simple solution-based method for the fabrication of highly-oriented carbon nanotube (CNT) array to be used in thin film transistors. We exploit liquid crystalline behavior of CNT solution near the receding contact line during tilted-drop casting and produced long-range nematic-like ordering of carbon nanotube stripes caused by confined micropatterned geometry. We further demonstrate that the performance of thin-film transistors is largely improved compared to TFT with random monolayer of CNTs with near-record career mobility. This approach has great potentials in low-cost, large-scale processing of high-performance electronic devices based on high-density oriented CNT films with record electrical characteristics such as high conductance, low resistivity, and high career mobility.
9:00 PM - Q5.37
Patterned Forest-Assembly of Single-Wall Carbon Nanotubes on Gold Using a Non-Thiol Functionalization Technique.
Haoyan Wei 1 , Sejong Kim 2 , Sang Nyon Kim 2 , Bryan Huey 1 , Fotios Papadimitrakopoulos 2 , Harris Marcus 1
1 Materials Science and Engineering Program, Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, Connecticut, United States, 2 Nanomaterials Optoelectronics Laboratory, Polymer Program, Institute of Materials Science, Department of Chemistry, University of Connecticut, Storrs, Connecticut, United States
Show AbstractAn approach of non-thiol functionalization of single-wall carbon nanotubes (SWNTs) on gold substrates was demonstrated via Fe3+-assisted self-assembly technique, which eliminated the time-consuming thiol adsorption process in the conventional methods. Upon immersion of gold substrates into pH 2.2 aqueous FeCl3 solution, FeCl3 directly hydrolyzed on the gold surface due to aqua regia effect and as a result films of FeO(OH)/FeOCl crystallites formed. Subsequent immersion into SWNT/dimethylformamide (SWNT/DMF) dispersion led to needle-like forest assemblies of SWNTs based on metal-assisted chelation and electrostatic interactions. Towards fabrication of SWNT patterns, two methods on localizing Fe3+/Au composite pads were investigated by either sputtering Au/Pd though a TEM grid or utilizing conventional photolithography. Such patterned Fe3+-functionalized Au structures provided the basis for the patterned site-specific forest-assembly of SWNTs as demonstrated by atomic force microscopy (AFM) measurement and resonance Raman spectroscopy.
9:00 PM - Q5.38
Thermodynamics Modeling of Defective Carbon Nanotubes in the Presence of Adsorbates.
Amanda Barnard 1
1 Department of Materials, University of Oxford, Oxford United Kingdom
Show AbstractThe growth of carbon nanotubes using hydrogen plasmas has received much attention in recent years, but far less attention has been given to the affect of adsorbed hydrogen on the relative stability of the final, possibly defective, structures. Presented here is a general analytical model for describing the energetics and relative stability of defective carbon SWNTs in the presence of adsorbates. The model is parameterized for the case of exohedral hydrogen, using results obtained from first principles simulations, and is constructed around experimentally relevant parameters such as the concentrations and configurations of adsorbates on the nanotube walls.
9:00 PM - Q5.39
Mechanism and Control of CNT Adsorption onto Silicon Dioxide Surfaces.
Timothy Burgin 1 , Justin Lewenstein 2 , Dennis Werho 3
1 Motorola Labs, Motorola, Tempe, Arizona, United States, 2 , Freescale Semiconductor, Tempe, Arizona, United States, 3 , Medtronic, Tempe, Arizona, United States
Show Abstract9:00 PM - Q5.4
Surface Reactions of Metal Catalysts in Ethanol-CVD Ambient at Low-pressure Studied by in-situ Photoelectron Spectroscopy.
Fumihiko Maeda 1 , Satoru Suzuki 1 , Yoshihiro Kobayashi 1 , Daisuke Takagi 2 , Yoshikazu Homma 2
1 NTT Basic Research Laboratories, NTT Corporation, and CREST, JST, Atsugi-shi, Kanagawa, Japan, 2 Department of Physics, Tokyo University of Science and CREST, JST, Shinjuku, Tokyo, Japan
Show Abstract9:00 PM - Q5.40
A Facile Solution Method to Synthesis of C60 Nanorods.
Bingbing Liu 1 , Lin Wang 1 , Guangtian Zou 1 , Agnieszka Iwasiewicz 2 , Bertil Sundqvist 2
1 , Jilin University, National Lab of Superhard Materials, Changchun China, 2 Department of Physics, Umea University, Umea Sweden
Show AbstractSynthesis of C60 nanorods is a challenging topic due to its unique structure and properties and their potential application in the nanometer scale field. We report here that a very facile solution evaporation method has been found to synthesize C60 nanorods with widths and thicknesses of the order of nanometers using m-xylene as a shape controller. These unusual nanorods can easily grow on various substrates such as glass and silicon. Nanorods with different diameters and length-to-diameter ratios can be synthesized under different growth conditions. The nanorods obtained are highly crystalline and single phase. A gradual expansion of the lattice constant is also found in the C60 nanorods as their widths decrease.
9:00 PM - Q5.41
First-principles Characterization of the Electrical, Vibrational, and Optical Properties of Carbon Nanotubes Functionalized with [2+1] Cycloadditions.
Young-Su Lee 1 , Nicola Bonini 1 , Nicola Marzari 1
1 Department of Materials Science and Engineering, and Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show Abstract9:00 PM - Q5.42
Novel Hybrid Polypropylene Nanocomposites with Montmorillonite and Single-Walled Carbon Nanotubes.
Emmanouil Vamvounis 1 , John Stanford 1 , Arthur Wilkinson 1 , Robert Young 1
1 School of Materials, University of Manchester, Manchester, Greater Manchester, United Kingdom
Show Abstract9:00 PM - Q5.43
Heat Transport of Carbon Nanotubes Embedded in a Metal Layer.
Yoichi Taira 1 , Kuniaki Sueoka 1
1 Tokyo Research Lab, IBM, Yamato Japan
Show AbstractCarbon nanotubes (CNT) show high thermal conductivity along the axis of their fiber shape. These materials can be used to realize a conformable and highly thermal conducting material called as a thermal interface material (TIM) for the heat transport between a VLSI and a heat sink. Since a half of the total heat resistance between the VLSI and the final heat exit is occupied by the TIM layer, and the VLSI power density is getting higher and higher, there is always a need for a better TIM having lower heat resistance. The TIM layer is also necessary to connect the VLSI package to the heatsink so that separately manufactured components are well connected thermally but a relative mechanical motion is allowed along with the temperature change when starting or shutting off the system. Since CNTs have very high thermal conductivity along the axis, it is most effective to align the CNTs along with the heat path for the lower heat resistance. Therefore a possible form CNT based TIM is densely packed aligned CNTs where the both ends of the nanotubes are connected to the heat source and the heat sink. To study how much thermal resistance can be reduced, we set up a model consisting of an aligned CNTs in contact with two copper blocks as a heat source and a heat sink. One interesting result of the modeling is that the resulting heat resistance is much higher than expected when the ends of CNT are just in touch with the copper block. When some length of the CNT is embedded in a metal layer, the resulting thermal resistance gets much lower and approaches to the value calculated by the CNT heat conductivity. This result indicates a need of special structure between the copper block and the CNTs so that the CNTs are embedded in metal layer.. The result is also consistent with our experimental measurement using gold as an interfacial material.
9:00 PM - Q5.45
Multifunctional Macro Architectures of Double-walled Carbon Nanotube Fibers.
Lijie Ci 1 , Saikat Talapatra 1 , Niramol Punbusayakul 1 2 , Robert Vajtai 1 , Pulickel. M. Ajayan 1
1 Department of Materials Science and Engineering, Rensselear Polytechnic Institute, Troy, New York, United States, 2 School of Bioresources and Technology, King Mongkut's University of Technology, Bangkok Thailand
Show AbstractMany applications are envisioned which will ultimately utilize macro-architectures fabricated using carbon nanotube building blocks. For example mechanically strong and long fibers of CNTs can act as superb electromechanical actuators, filler materials in composites, power cables and electrodes. In this presentation we report on the fabrication, characterization and application of long spun fibers of double walled carbon nanotubes (DWCNT). The DWCNTs have a higher structure stability and oxidation resistance than single walled CNTs (SWCNTs) and have properties such as high strength, low density and admirable thermal and electrical conductivity. A simple and scalable pulling-drying process of spinning pure DWCNT fibers out of nanotube “cotton” is described. Fibers having a wide range of diameters (10 μm -100 μm) and possessing high mechanical strength (tensile strength ~ 299 MPa, and Young’s modulus ~8.3 GPa) can be drawn using this process. Electrochemical tests using the DWCNT fibers as electrodes indicate that their surfaces possess very fast electron transfer kinetics and can be used as excellent working electrode for the electrochemical and bio sensing applications. Field emission tests performed on individual DWCNT fiber revealed a very low turn-on electric field (~0.4 V/mm) and a very high emission current density (~9 A/cm2 at the electric field of 1.0 V/mm). A very high field enhancement factor, b (~ 2.2×104) was also obtained form the nanotubes. Our findings show the possibility of using DWCNTs fibers as excellent components in various device architectures.
9:00 PM - Q5.46
Strengthened, Aligned Carbon Nanotube Film via Vapor Phase Infiltration of Carbon.
Xuesong Li 1 , Lijie Ci 1 , Pulickel Ajayan 1
1 Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States
Show AbstractDue to the low density and high porosity of aligned carbon nanotube (ACNT) films, the as-grown ACNT film has low effective compression modulus and electrical and thermal conductance since the interstitial space between nanotubes is only occupied by air. Filling the space in the films with solid materials could modify the properties of the ACNT films and render them useful for applications that require increased robustness or hardness, protection from oxidation at high temperatures and other damaging ambients, or increased effective electrical and thermal conductance. In this study, the growth of ACNT films was conducted using a vapor phase catalyst delivery method by chemical vapor deposition (CVD) at 770 C using a mixture of xylene and ferrocene vapors. By simply increasing the reaction time for the nanotube growth, deposition of pyrolyzed carbon created carbon infiltrated ACNT/C composite films. Scanning electron microscope (SEM) analysis and microbalance measurements showed that after infiltration, the diameters of nanotubes and bulk density of ACNT film could be increased by an order of magnitude. TEM and Raman scattering analysis showed that the ACNT/C composite structure included a CNT core and a partially graphitized carbon shell. Compression tests showed that the modulus of the ACNT film could be increased by nearly 2000 times. These property enhanced ACNT film could have several potential applications, making up for the low density of as prepared ACNT films.
9:00 PM - Q5.47
Stability and Crystallization Behaviors of Regioreguler Poly(3-hexylthiophene) Nanotube Composites.
Ananta Adhikari 1 , Mircea Chipara 2 , Chang Ryu 3 , Pulickel Ajayan 4 , Hassaram Bakhru 1
1 College of Nanoscale Science & Engineering, State University of New York, Albany, New York, United States, 2 Department of Chemistry , Indiana University, Bloomington, Indiana, United States, 3 Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, New York, United States, 4 Department of Material Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States
Show Abstract9:00 PM - Q5.48
Work Function of Functionalized Single-wall Carbon Nanotubes.
Nicholas Miller 1 , Janet Ryu 1 , Nicola Marzari 1
1 Department of Materials Science and Engineering, Massachusetts Institute of Engineering, Cambridge, Massachusetts, United States
Show Abstract9:00 PM - Q5.49
In-situ Raman Study on Lithium Insertion into Double Walled Carbon Nanotubes-derived Bucky Paper.
Yoong Ahm KIm 1 , Hayashi Takuya 1 , Muramatsu Hiroyuki 1 , Endo Morinobu 1 , Terrones Mauricio 2 , Dresselhaus Mildred S. 3
1 , Shinshu University, Nagano Japan, 2 , IPICYT, San Luis Potosí Mexico, 3 , Massachusetts Institute of Technology, Massachusetts, California, United States
Show AbstractWe carried out the Li+ storage behaviors of highly pure single wall carbon nanotube (SWNT)- and double walled carbon nanotubes (DWNT)-buckypapers (consisting of entangled tube bundles) as an anode material in lithium ion batteries (LIBs) using an in-situ the Raman technique. The fabrication of these SWNT- and DWNT-buckypaper via a filtering process resulted from entangled long nanotube bundles of either SWNTs or DWNTs, in which the nanotubes are packed into hexagonal arrays. These thin, flexible and mechanically tough SWNT- and DWNT-foils exhibit an analogue behavior to hard carbons upon Li ion insertion at different voltages. From our studies, we mainly suggest the interstitial space in bundled nanotubes as the Li+ storage sites in nanotube-foils. In detail, Raman changes as a function of Li+ addition will be discussed.
9:00 PM - Q5.5
Three-Dimensional Single-Walled Carbon Nanotube Architecture using Suspended Catalyst Particles.
Tomoya Ito 1 , Toshio Ogino 1 2
1 Electrical and Computer Engineering, Yokohama National University, Yokohama Japan, 2 , Japan Science And Technology Agency, Kawaguchi Japan
Show Abstract9:00 PM - Q5.50
Subwavelength Microscopy with Elongated Nanostructures.
Pavel Dorozhkin 1 , Konstantin Mochalov 1 , Sergey Saunin 1 , Victor Bykov 1
1 , NT-MDT Co., Zelenograd Moscow Russian Federation
Show Abstract9:00 PM - Q5.51
Binding of Charged Supramolecular Complexes to Carbon Nanotubes.
Harsh Chaturvedi 2 , Andrea Giordano 1 , Ryan Phillips 1 , Thomas Younts 1 , Jordan Poler 1 2
2 Center for Optoelectronics and Optical Communications, UNC Charlotte, Charlotte, North Carolina, United States, 1 Chemistry, UNC Charlotte, Charlotte, North Carolina, United States
Show Abstract9:00 PM - Q5.52
Resonant Raman Scattering Excitation Profiles from a 1D System.
Yan Yin 1 , A. Vamivakas 2 , A. Walsh 1 , S. Cronin 3 , M. Unlu 2 1 , B. Goldberg 1 2 , A. Swan 2 1
1 Physics Department, Boston University, Boston, Massachusetts, United States, 2 Electrical and Computer Engineering Department, Boston University, Boston, Massachusetts, United States, 3 Electrical Engineering Department, University of Southern California, Los Angeles, California, United States
Show Abstract9:00 PM - Q5.53
Study on Double-walled Carbon Nanotube X-junction Formation.
Takuya Hayashi 1 , Yuta Shiba 1 , Hiroyuki Muramatsu 1 , Daisuke Shimamoto 1 , Satoru Naokawa 1 , Shusuke Furui 1 , Yoong-Ahm Kim 1 , Morinobu Endo 1
1 , Shinshu University, Nagano Japan
Show Abstract9:00 PM - Q5.54
Sodium Chloride-Catalyzed Oxidation of Multi-Walled Carbon Nanotubes for Environmental Benefit.
Kenji Takeuchi 1 , Takeyuki Tajiri 1 , Ki Chul Park 1 , Morinobu Endo 1 , Mildred Dresselhaus 2
1 , Faculty of Engineering, Shinshu University, Nagano Japan, 2 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show Abstract9:00 PM - Q5.55
Imaging and Engineering Strain in Individual Single-Wall Carbon Nanotubes.
Hyungbin Son 1 , Xiaojie Duan 2 , Jin Zhang 2 , Georgii Samsonidze 1 , Yingying Zhang 2 , Ervin Mile 1 , Mildred Dresselhaus 1 , Zhongfan Liu 2 , Jing Kong 1
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 , Peking University, Beijing China
Show Abstract9:00 PM - Q5.56
Embedding Nanoparticles in the Walls of Carbon Nanotubes.
Davide Mattia 1 , Gulya Korneva 1 , Yury Gogotsi 1
1 Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania, United States
Show Abstract9:00 PM - Q5.57
Boron-induced Coalescence in Double Walled Carbon Nanotubes.
Hiroyuki Muramatsu 1 , Kim Yoong-Ahm 1 , Takuya Hayashi 1 , Morinobu Endo 1
1 , Shinshu University, Nagano Japan
Show AbstractThe interconnection and coalescing of double walled carbon nanotubes (DWNTs) have attracted much attention of various researchers, because it is possible to fabricate complex architectures such as nanotube junction and networks that exhibit novel electronic and mechanical properties. Recently, we demonstrated that the outer shells of two adjacent DWNTs could coalesce via a zipping process by high temperature thermal treatment (ca. 2100oC). In addition, with the help of boron atoms, the temperature of merging in DWNTs is lowered by ca. 600oC, when compared to conventional DWNTs. Here, we have carried out systematic studies on boron-induced changes in DWNTs using Raman, UV, TEM, SEM and TGA analysis.
9:00 PM - Q5.61
Novel Metallic Substrate Mediated Growth of Aligned CNT Films and its Thermal Transport on Metal-NT Interface.
Sunil Pal 1 , Saikat Talapatra 2 , Swastik Kar 2 , Robert Vajtai 3 , Linda Schadler 2 3 , Theodorian Borca-Tasciuc 1 3 , Pulickel Ajayan 2 3
1 Mechanical, Aerospace, & Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States, 2 Materials Science & Engineering, Rensselaer Polytechnic Institute, Tory, New York, United States, 3 Rensselaer Nanotechnology Center, Rensselaer Polytechnic Institute, Troy, New York, United States
Show Abstract9:00 PM - Q5.62
Synthesis of TCNQ-Cu organic nanowires and directed growth into devices
Kai Xiao 1 , Jing Tao 2 , Ilia Ivanov 1 , Alex Puretzky 1 , Zuqin Liu 1 , Stephen Pennycok 2 , David Geohegan 1 2
1 Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 2 Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
Show AbstractSingle-crystal, one-dimensional semiconductor nanostructures are critical building blocks for nanoscale optical and electronic devices. Here we report a simple method for the chemical vapor deposition synthesis of single-crystal nanowires of many organic semiconductor materials. TCNQ-Cu is an organic charge-transfer complex with unique electrical properties which has applications in both optical and electrical recording media. This talk reports the direct synthesis and integration of semiconducting TCNQ-Cu organic nanowires into prefabricated electrode structures at temperatures compatible with growth on plastics. The organic nanowires are single crystalline and semiconducting, and can be reproducibly grown directly between patterned metal electrodes in a scalable process compatible with on-chip microelectronics without the need for post-processing, facilitating the integration of organic nanowire electronics into larger-scale systems. Current-voltage characteristic curves indicate that the semiconducting TCNQ-Cu nanowires have excellent contact with the electrodes and exhibit bistable switching properties which potentially could be used for high-density memory devices. This research was conducted in the Functional Nanomaterials Theme at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Division of Scientific User Facilities, U.S. Department of Energy.
9:00 PM - Q5.63
Experimental Study of Factors Controlling the Production of Micro- and Nanofibers by Laser Spinning.
Felix Quintero 1 2 , Adrian Mann 2 , Juan Pou 1 , Fernando Lusquiños 1 , Antonio Riveiro 1
1 Applied Physics, University of Vigo, Vigo, Pontevedra, Spain, 2 Materials Science & Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States
Show AbstractNew applications of glass fibers with diameters in the nanometric range are quickly evolving. We have developed a new method, Laser Spinning, for the production of glass fibers with diameters in the nanometer to micrometer scale. The technique allows large quantities of nanofibers to be made with specific, controllable chemical compositions. This will potentially open up a whole new range of applications for the fibers.In Laser Spinning a high power laser is employed to melt the precursor solid material, while the melt forms glass fibers as a result of its viscous elongation and cooling by the drag force and convective heat transfer promoted by the gas jet. The fiber size and efficiency of the process are influenced by the operating conditions which must be control to give the desired characteristics. An analysis of the influence of several factors controlling the morphology and composition of the glass fibers has been performed experimentally. The results and conclusions of this study will be presented in this poster.The influence of the gas jet pressure and the laser power on the morphology and distribution of diameters of the fibers has been evaluated by means of electron microscopy analysis. The dependence of the average composition and homogeneity on the composition and microstructure of the precursor material has been studied using XPS and TOF-SIMS. The experimental results are explained based on a theoretical explanation of the process of Laser Spinning. This leads ultimately to the deduction of a set of rules regarding the influence of the factors studied on the production of nanofibers by Laser Spinning.
9:00 PM - Q5.64
Novel Organic Nanohelices via Vapor-Solid Phase Transformation Reaction
Seok Min Yoon 1 , Bonghwan Chon 1 , Wonjung Kim 1 , Sang Joo Lee 2 , Taiha Joo 1 , Seung-Koo Shin 1 , Jin Yong Lee 3 , Hee Cheul Choi 1
1 department of chemistry, pohang university of science and technology, Pohang Korea (the Republic of), 2 Center for Computational Biology and Bioinformatics, Korea Institute of Science and Technology Information, 52 Eoeun-dong, Yuseong-gu, Daejeon Korea (the Republic of), 3 chemistry, Sungkyunkwan University, 300 Chunchun-Dong, Jangan-Gu , Suwon Korea (the Republic of)
Show Abstract9:00 PM - Q5.8
Optimization of the Production Single-Walled Carbon Nanotubes with Fe-Mo/MgO as Catalyst.
Marcio Lima 1 2 , Mônica de Andrade 1 2 , Siegmar Roth 1 , Carlos Bergmann 2
1 von Klitzing's department, Max Planck Institute for Solid State Research, Stuttgart, Baden-Württemberg, Germany, 2 Materials Department, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
Show AbstractGreat attention have ben focused on Thermal Chemical Vapour Deposition (TCVD) due to its great potential for scale-up the synthesis of carbon nanotubes (CNTs) with powder catalysts. The main purpose of this work is to optimize the production of Fe-Mo/MgO Single-Walled Carbon Nanotubes (SWNTs) through TCVD. In order to that, the composition of the catalyst (Fe:Mo precursos ratio), the catalyst preparation route and synthesis conditions were evaluated (temperature, time and carbon source). Ethanol and Hexane were tested as carbon sources. Catalysts were produced through a Solution Combustion Synthesis technique, which allows a fast preparation of single or several oxides. Iron and molybdenum oxides dispersed in magnesium oxide (MgO) matrix form an inexpensive SWNT catalyst and the easily dissolution of the MgO in mild acids facilitates the purification process. In situ characterization by electrical conductivity of the catalysts were also used to evaluated the effect of several synthesis parameters. The diameter of the nanotubes were not significantly affected by the carbon source. Higher yields of SWCTs were obtained using hexane but also more deposition of amorphous carbon was observed. It was found that molybdenum addition in small amount (Fe:Mo≤20) causes an increasing in the G/D ratio and yields SWNTs, but higher amount causes an increase in the number of walls of CNTs and also the production of undesirable carbon nanostructures (nanofibers and carbon onions).
9:00 PM - Q5.9
Structural Investigation of Nano-Carbon Produced by Electric Arc-Discharge in Non-Conventional Environments.
Emanuela Piscopiello 1 , Marco Vittori Antisari 2 , Daniele Mirabile Gattia 2 , Vittoria Contini 2 , Maria Rita Mancini 2 , Amelia Montone 2 , Renzo Marazzi 2
1 UTS MAT, ENEA-c.r. Brindisi, Brindisi Italy, 2 UTS Materiali e Nuove Tecnologie, ENEA-c.r. Casaccia, Rome Italy
Show Abstract
Symposium Organizers
Prabhakar Bandaru University of California-San Diego
Morinobu Endo Shinshu University
Ian Kinloch University of Cambridge
Apparao M. Rao Clemson University
Q6: Novel CNT morphologies and Nanostructure Assembly
Session Chairs
Tuesday AM, November 28, 2006
Room 312 (Hynes)
9:00 AM - **Q6.1
Emerging Nanodevices made with Branched Nanostructures.
Hongqi Xu 1
1 Division of Solid State Physics, Lund University, Lund Sweden
Show Abstract9:30 AM - Q6.2
Electrical Property-Structure Correlation of Y Branched Carbon Nanotubes.
Jeongwon Park 1 , Prabhakar Bandaru 1 , Apparao Rao 2
1 Materials Science and Engineering, University of California, San Diego, La Jolla, California, United States, 2 Department of Physics and Astronomy, Clemson University, Clemson, South Carolina, United States
Show Abstract9:45 AM - Q6.3
Towards an AC Dielectrophoresis Toolkit for Assembling Carbon Nanotube Devices.
Sarbajit Banerjee 1 2 , Brian White 1 2 , Limin Huang 1 2 , Blake Rego 1 2 , Stephen O'Brien 1 2 , Irving Herman 1 2
1 Nanoscale Science and Engineering Center, Columbia University, New York, New York, United States, 2 Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York, United States
Show Abstract10:00 AM - Q6.4
Techniques Toward lLrge-scale Chiral Separation of Single-walled Carbon Nanotubes via Selective Precipitation.
Timothy McDonald 1 2 , Jeffrey Blackburn 1 , Chaiwat Engtrakul 1 , Garry Rumbles 1 , Michael Heben 1
1 Basic Science, National Renewable Energy Lab, Golden, Colorado, United States, 2 Applied Physics, Columbia University, New York, New York, United States
Show Abstract10:15 AM - Q6.5
Diameter and Chirality Dependent Characterization and Separation of Single Wall Carbon Nanotubes.
Fotios Papadimitrakopoulos 1 , Zhengtang Luo 1 , Sang Nyon Kim 1 , Stephen Doorn 2 , Lisa Pfefferle 3 , Gary Haller 3
1 Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, Connecticut, United States, 2 Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 3 Department of Chemical Engineering, Yale University, New Haven, Connecticut, United States
Show Abstract10:30 AM - Q6.6
Lithography-free In Situ Ohmic Contacts to Single-Walled Carbon Nanotubes.
Aaron Franklin 1 2 , Joshua Smith 1 2 , Matthew Maschmann 1 3 , David Janes 1 2 , Timothy Sands 1 2 4 , Timothy Fisher 1 3
1 Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, United States, 2 Electrical & Computer Engineering, Purdue University, West Lafayette , Indiana, United States, 3 Mechanical Engineering, Purdue University, West Lafayette , Indiana, United States, 4 Materials Engineering, Purdue University, West Lafayette , Indiana, United States
Show AbstractSingle-walled carbon nanotubes (SWNTs) have been integrated into electronic and chemical sensing devices because of their exceptional electronic transport properties and potential for high-density integration. Devices produced by dispersing or synthesizing SWNTs across lithographically defined metallic contact pads have been limited to two-dimensional planar architectures, dictated in large part by contact metallization techniques. Although horizontal structures have proven invaluable for examination of SWNT transport properties and functional material selection, their flexibility is severely limited and precludes the exploitation of the nanometer-scale diameter of SWNTs as a scaling metric. The evolution of SWNT devices beyond planar, two-dimensional configurations will require contact metallization methods outside the scope of current lithographic techniques. Though plans for more complicated vertical carbon nanotube devices have been proposed in recent years, the means to establish electrical contact and structural support to individual vertical SWNTs has not been directly addressed. In part, the inability to synthesize vertical SWNTs in predefined locations has hindered research into the topic. We present both a robust vehicle to synthesize vertical SWNTs in channels suitable for device integration and a facile means to contact the top and bottom of SWNTs simultaneously without the use of a single lithographic procedure. Using microwave plasma-enhanced chemical vapor deposition (PECVD), SWNTs were synthesized from a Fe catalyst embedded in the pore walls of a PAA template. In this structure, SWNTs originate from the localized embedded catalyst layer and emerge at the top PAA surface, forming vertical channels within the pores. The SWNTs continue to lengthen along the top PAA surface after emerging from the pores. TEM micrographs and micro-Raman spectra confirm the existence of SWNTs with diameters in the range of 1-2 nm. The development of in situ top and bottom contacts to the SWNTs is achieved simultaneously by electrodepositing Pd into the pore bottoms. Using a Ti layer beneath the PAA template as the working electrode, Pd is electrodeposited within the pores to form nanowires that contact the bottom of the SWNTs. Once the Pd nanowires reach the level of the catalyst layer, they contact the bottom of the SWNTs emerging from the catalyst layer. After contact is established, continued deposition yields Pd nanoclusters formed annularly on portions of the SWNTs on the top PAA surface. Variation of the electrodeposition conditions enables control over the size of the Pd nanoclusters, as well as their morphology. Creating the most stable deposition environment yields mono-crystalline Pd nanocubes that form concentrically around the SWNTs. This structure enables fabrication of vertical SWNT devices such as field effect transistors, field emission arrays, and sensing networks.
10:45 AM - Q6.7
Focused Ion Beam Induced Growth of Antimony Nanowires.
Christoph Schoendorfer 1 , Alois Lugstein 1 , Youn-Joo Hyun 1 , Peter Pongratz 2 , Emmerich Bertagnolli 1
1 Institute for Solid State Electronics, Vienna University of Technology, Vienna Austria, 2 Institute for Solid State Physics, Vienna University of Technology, Vienna Austria
Show AbstractQ7: Raman Spectroscopy
Session Chairs
Tuesday PM, November 28, 2006
Room 312 (Hynes)
11:30 AM - **Q7.1
Phonon-Phonon Interactions in Suspended Carbon Nanotubes.
Jose Menendez 1
1 Department of Physics, Arizona State University, Tempe, Arizona, United States
Show AbstractThe combined dynamics of electrons and phonons determines the transport properties of materials. When the electron-phonon coupling is very strong for a particular vibrational mode (for example, LO phonons in polar semiconductors), a large non-equilibrium population is established for this mode under device operating conditions. In such cases, the purely anharmonic decay rate of the mode is of particular technological importance, since the non-equilibrium phonons that are not annihilated through phonon-phonon interactions increase the electron-phonon scattering rates.
Recent experiments indicate that electrons tunneling into a metallic carbon nanotube induce the establishment of a non-equilibrium population for the radial breathing mode (RBM).1 Thus the anharmonic lifetime of this mode is of interest for transport phenomena in nanotubes.The study of anharmonic interactions in carbon nanotubes is also of fundamental interest. While the tunneling experiments suggest that the RBM anharmonic lifetime is as long as 10 ns, the room temperature linewidth of this Raman-active active mode has been reported to be around 3 cm-1, which corresponds to a lifetime of approximately 2 ps. A discrepancy of more than three orders of magnitude suggests that the theoretical framework connecting time domain and frequency domain experiments needs revision in the case of carbon nanotubes.
We present new Raman scattering results from suspended carbon nanotubes showing that the natural FWHM at room temperature can be as small as 0.7 cm-1. This width, while much smaller than previously reported, corresponds to a lifetime of 7.6 ps, still three orders of magnitude shorter than the tunneling results. We propose a model to explain the discrepancy based on the existence of a non-equilibrium population for the RBM and its decay products. This has already been observed in a few cases in three-dimensional crystals, but we show that non-equilibrium secondary phonons are much more likely to be found in one-dimensional systems. This scenario can lead to time-domain experiments showing lifetimes approaching the nanosecond range, while at the same time Raman experiments would detect linewidths on the order of 1 cm-1, in the picosecond range. These results may have wide-ranging implications for the use of carbon nanotubes as electrical interconnects.
This work was done in collaboration with R. Rao, A.M. Rao, and C.D. Poweleit and supported by NSF under grant DMR-0244290.
1B.J. LeRoy, S.G. Lemay, J. Kong, and C. Dekker, Nature 432, 371 (2004).
12:00 PM - Q7.2
Nanowires Enabling Signal Enhanced Nano-Raman-Spectroscopy.
Michael Becker 1 , Vladimir Sivakov 2 3 , Ulrich Gösele 2 , Gudrun Andrä 3 , Ruth Geiger 4 , Hans-Juergen Reich 4 , Samuel Hoffmann 5 , Johann Michler 5 , Silke Christiansen 1 3
1 , Martin-Luther University, Halle Germany, 2 , Max-Planck-Institute for Microstructure Physics, Halle Germany, 3 , Institute for Physical Hightechnology e.V., Jena Germany, 4 , Horiba Jobin Yvon GmBH, Bensheim Germany, 5 , EMPA, Thun Germany
Show Abstract12:15 PM - Q7.3
One and Two Phonon Resonant Raman Scattering from Single Wall Carbon Nanotubes.
Anthony Vamivakas 1 , Yan Yin 2 , Andrew Walsh 2 , Selim Unlu 1 , Bennett Goldberg 2 , Anna Swan 1
1 Electrical and Computer Engineering, Boston University, Boston, Massachusetts, United States, 2 Physics, Boston University, Boston , Massachusetts, United States
Show Abstract Single wall carbon nanotubes (SWNTs) represent prototypical one-dimensional systems that are under intense study to understand their basic physical properties. The one dimensional character of SWNTs results in sharp van-Hove singularities in the density of states for both the electronic and vibronic tube excitations. Resonant Raman scattering is an optical technique that allows one to simultaneously probe the vibrational and electronic properties of SWNTs. In one phonon resonant Raman scattering (1phRRS), the shift between incoming and Raman scattered photon provides information about zone-center phonon energies. In addition, the scattering cross-section reflects singularities in the tube’s electronic structure and therefore permits determination of electronic excitation energies. Recent theoretical and experimental work has concluded that the tube’s electronic excitations are excitonic in nature. We have modeled the 1phRRS cross-section considering the effect of both free electron and excitonic intermediate states on the Raman process and found that for the range of exciton binding energies in the tubes we measure, there is no appreciable change in the resonance excitation profile (the cross-section as a function of laser energy). In two phonon Resonant Raman scattering (2phRRS), the scattering cross-section not only has features associated with electronic transition energies in the tube, but also is modulated by the density of states of the two phonons that participate in the scattering event. We have extended earlier work on achiral tubes to calculate both the phonon dispersion and density of states for chiral SWNTs. We have been able to use the density of phonon states to calculate the two phonon scattering cross-section for tubes of arbitrary chirality.
12:30 PM - Q7.4
Raman Antenna Effect of Semiconducting Nanowires.
Qihua Xiong 1 , G. Chen 1 , M. Pellen 2 , J. Petko 2 , D. Werner 2 , Peter Eklund 1
1 Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, United States, 2 Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States
Show Abstract12:45 PM - Q7.5
Counting Graphene Layers by Raman Spectroscopy
Andrea C. Ferrari 1 , Jannik Meyer 2 , Vittorio Scardaci 1 , Cinzia Casiraghi 1 , Michele Lazzeri 3 , Francesco Mauri 3 , Stefano Piscanec 1 , Da Jiang 4 , Kostya Novoselov 4 , Andre Geim 4
1 Engineering, University of Cambridge, Cambridge United Kingdom, 2 , Max Plank Institute for Solid State Research, Stuttgart Germany, 3 , Institut de Mineralogie et de Physique des Milieux Condenses, Paris France, 4 Department of Physics and Astronomy, University of Manchester, Manchester United Kingdom
Show AbstractGraphene, a single, one-atom-thick sheet of carbon atoms in a honeycomb lattice, is the two-dimensional (2D) building block for carbon allotropes of every other dimensionality. It can be stacked into 3D graphite, rolled into 1D nanotubes, or wrapped into 0D buckyballs. Only very recently graphene has been produced in its free state [1]. This has fuelled research in 2D carbons and highlighted their remarkable electronic properties [2,3]. Graphene is a ballistic conductor in which electrons mimic the behaviour of massless, relativistic particles [2,3]. Electron transport is governed by the (relativistic) Dirac equation (rather than the Schrödinger equation) and this allows access to the rich and subtle physics of quantum electrodynamics in a condensed matter experiment Here we present the Raman fingerprint of an isolated graphene layer and its evolution with the number of layers [4]. This is supported by the definitive identification of free-standing single and bi-layers by transmission electron microscopy and electron diffraction. We show that graphene’s electronic structure is uniquely captured in its Raman spectrum. We identify the unique features of its Raman spectrum, which fingerprints graphene amongst all other carbon allotropes. We compare its spectrum to that of n graphene layers having the same stacking as graphite, with n=2 to 28. We demonstrate that the Raman spectrum evolution with increasing number of layers uniquely reflects the evolution of the electronic structure and electron-phonon interactions. This makes Raman spectroscopy is a quick, high-throughput, non-destructive technique for the unambiguous identification of graphene layers, which is critically lacking in this emerging research area. Finally we discuss the implications for the interpretation of the Raman spectra of single and double wall nanotubes. 1 K. S. Novoselov et al. Proc. Natl. Acad. Sci. USA 102, 10451 (2005) 2 K S Novoselov et al, Science 306, 666 (2004); Nature 438, 197 (2005) 3 Y Zhang et al Nature 438, 201 (2005) 4 A. C. Ferrari et al cond-mat/0606248 (2006)
Q8: Inorganic nanowires
Session Chairs
Tuesday PM, November 28, 2006
Room 312 (Hynes)
2:30 PM - Q8.1
Controlled Synthesis of Millimeter-Long Silicon Nanowires with Uniform Electronic Properties.
Won Il Park 1 , Gengfeng Zheng 1 , Xiaocheng Jiang 1 , Bozhi Tian 1 , Charles Lieber 1 2
1 Department of Chemistry and Chemical Biology, Harvard University, Cambridg, Massachusetts, United States, 2 Division of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts, United States
Show Abstract2:45 PM - Q8.2
Hetero-epitaxy of Germanium Nanowires on Silicon Substrates from Gold Colloids and Subsequent Gold Catalyst Removal.
Jacob Woodruff 1 , Joshua Ratchford 1 , Christopher Chidsey 1
1 Chemistry Department, Stanford University, Stanford, California, United States
Show AbstractGold catalyzed, chemical-vapor-deposition grown semiconductor nanowires are being investigated as promising materials for active device elements in 3D electronics, solar cells, biosensors, and many more applications. In particular germanium nanowires are interesting due to their sub-400°C growth temperatures. The ability to control the nanowire’s orientation and diameter and the ability to remove the gold catalyst after growth are crucial, however, in order for most of these applications to be realized.One technique that we have investigated to gain orientational control is to induce hetero-epitaxy with an underlying silicon crystalline substrate during growth. Previous studies have focused on nanowires grown from evaporated films of gold on silicon, which result in a wide range of nanowire diameters. Because the nanowire’s diameter is determined by the starting gold catalyst size, well-controlled homogeneous nanowire diameters can be obtained by using commercially available gold colloid solutions with narrow size distributions. However, gold colloid deposition techniques most used in literature that rely on “linkers” such as aminopropyltriethoxysilane (APTES) or poly-L-lysine, are shown to inhibit epitaxial growth of nanowires on silicon. It is hypothesized that this is due to either oxide formation or chemical modification of the surface by the linker during the colloid deposition procedure. We have developed a new, linker free, method for depositing gold colloids onto silicon that inhibits silicon oxide formation and results in hetero-epitaxy of germanium nanowires. Studies of hetero-epitaxy of germanium nanowires on silicon substrates using this method are presented.In order to remove the gold catalysts from the tip and surface of the nanowire after growth we have developed novel chemical etching techniques. It was found that iodine based gold etches commercially made for silicon quickly etch away germanium nanowires. We have developed a novel technique to passivate the germanium nanowires and keep them passivated during etching to allow removal of gold without destroying the nanowires. We present gold catalyst etch studies from germanium nanowires using these techniques.
3:15 PM - Q8.4
Surface and Electrical Characterization of InAs Nanowires.
Qingling Hang 1 , Fudong Wang 2 , Dmitry Zemlyanov 1 , William Buhro 2 , David Janes 1
1 , Purdue University, West Lafayette, Indiana, United States, 2 , Washington University, St. Louis, Missouri, United States
Show Abstract3:30 PM - Q8.5
Shape Control Growth of Crystalline Lanthanum Hexaboride Nanostructures.
Joseph Brewer 1 , Nirmalendu Deo 1 , Chin Li Cheung 1 2
1 Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, United States, 2 Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska, United States
Show AbstractMaterials of low work function and high aspect ratios are of great importance for the development of new field-induced electron emitters using low applied voltage. Lanthanum hexaboride (LaB6) is among one of the known materials with the lowest work function. Though the synthesis of LaB6 nanowires was reported in the literature, the shape control synthesis of robust LaB6 nanostructures is lacking. Here, we report our development of a low temperature CVD process for the growth of single crystalline LaB6 nano-obelisks and nanowires. Growth of these obelisks and wires was controlled by the substrate lattice orientation, catalyst particles, and the temperature of the reaction. Diameters of the nano-obelisk tips range from 20 to 50 nm. The nanowire diameters range from 20 to 100 nm with a preferred (100) growth orientation. The shape control growth mechanism of these different nanostructures and its application for fabrication of field emitter arrays will also be discussed.
Q9: III-V Semiconductor Nanowires
Session Chairs
Tuesday PM, November 28, 2006
Room 312 (Hynes)
4:15 PM - **Q9.1
Inorganic Nanowires: Novel Synthesis Approaches and Applications
Mahendra Sunkara 1
1 Chemical Engineering, University of Louisville, Louisville, Kentucky, United States
Show AbstractThe synthesis of nanowires in bulk amounts with control on growth direction and size is important, but has not been fully accomplished. Toward this goal, our group has been working on several new synthesis strategies for bulk production of inorganic nanowires. These strategies are non-traditional compared to the well accepted metal-cluster templated vapor-liquid-solid route, and they can be generalized as (a) bulk nucleation and growth of nanowires from quasi-immiscible solvents such as low-melting metal melts (b) direct nucleation and growth of oxide nanowires from metal foils and (c) nucleation and growth of nanowires directly from the vapor phase. In all of the above cases, the nucleation step controls the size of the resulting nanowires. A rational basis for nanowire synthesis using low-melting point metal melts is developed and is verified using the nucleation and growth kinetics of Ge nanowires. The experimental demonstrations for nanowire synthesis were however performed for a wide-range of materials systems involving nitrides, oxides, sulfides, metals, semiconductors and several compound semiconductors. Kinetic Monte-Carlo (KMC) simulations were also performed to understand the relationship between the growth kinetics and the resulting growth directions for nanowires. The simulation results suggest that the fast growth kinetics lead to <100> growth direction compared to <111> growth direction under slow growth kinetics for diamond-cubic structured material systems. The experimental results from our group on Ge nanowire growth kinetics from Ga melts and other groups on epitaxial nanowires consistently validate the KMC simulation findings. Finally, this presentation will highlight our studies on the behavior of nanowires in applications requiring bulk quantities such as (a) dispersions, (b) gas sensing, (c) composites and (d) solar cells. The results show that the nanowires with their high aspect ratios have inherent advantages and perform better than their nanoparticle counterparts.
4:45 PM - Q9.2
Nucleation Mechanism for Catalyst-free GaN Nanowires.
Kris Bertness 1 , A. Roshko 1 , L. Mansfield 1 , I. Levin 2 , N. Sanford 1
1 Mail Stop 815.04, NIST, Boulder, Colorado, United States, 2 , NIST, Gaithersburg, Maryland, United States
Show AbstractWe have examined the initial steps for catalyst-free growth of GaN nanowires by molecular beam epitaxy on Si (111) substrates with AlN buffer layers. We find that the nanowires nucleate in the center of small, dense hexagonal pits that form in the GaN layer immediately above the AlN buffer. Both field emission scanning electron microscopy (FESEM) and atomic form microscopy (AFM) indicated that the sidewalls of the pits were tilted approximately 43 to 50 ° from the substrate normal, which is near the 43.2° angle expected for (1 0 -1 2) planes. This orientation resulted pit sidewalls with the same azimuthal alignment as the (1 0 -1 0) planes that formed the sidewalls of the nanowires. We have shown previously that the nanowires grow along the [0 0 0 1] axis with regular hexagonal cross-section. The nanowires were 20 to 500 nm in diameter and had lengths up to 15 μm. These wires form spontaneously under high N-to-Ga ratios for a growth temperature range of about 810 to 830 °C, without the use of a catalyst. Recent results on the polarity of GaN nanowires will also be presented. In contrast to other catalyst-free GaN nanowire growth with MBE,[1,2] our nucleation studies show that the use of an AlN buffer layer is essential to the regular formation of the nanowires and GaN underlayers under our growth conditions. Our typical AlN buffer layer was 40 nm to 50 nm thick. We also observed that higher atomic nitrogen concentrations promoted a higher density of nanowires, and higher concentrations of excited molecular species increased the growth rate of the nanowires and thick underlayers. Based on several observations concerning the growth of the GaN nanowires, including the absence of any observation of Ga droplets at the end facets, we conclude that the nucleation mechanism for nanowires is based on variations in sticking coefficients for Ga on the various planes formed by GaN, and not on Ga droplet formation. [1] J. Ristić, M. A. Sánchez-García, E. Calleja, J. Sanchez-Paramo, J. M. Calleja, U. Jahn, and K. H. Ploog, Phys. Status Solidi A-Appl. Res. 192, 60-66 (2002).[2] A. Kikuchi, M. Kawai, M. Tada, and K. Kishino, Jpn. J. Appl. Phys. Part 2 43, L1524-L1526 (2004).
5:00 PM - Q9.3
Electronic Structure of Donor and Acceptor Impurities in Semiconductor Nanowires.
Mamadou Diarra 1 , Yann-Michel Niquet 2 , Christophe Delerue 1 , Guy Allan 1
1 ISEN, IEMN (UMR CNRS 8520), LILLE France, 2 DRFMC/SP2M/L_Sim, CEA, Grenoble France
Show Abstract5:15 PM - Q9.4
Study of Individual Gallium Nitride Nanowires Grown by HVPE and CVD.
Joonah Yoon 1 2 , Ilan Shalish 2 , George Seryogin 2 , Venkatesh Narayanamurti 2
1 Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States
Show AbstractGallium Nitride (GaN) is a technologically important wide bandgap semiconductor material. Further more, the current development in nanowire field can lead to a better performance and efficiency for existing devices as well as a new breed of devices. The focus of our work is to shed light on the unique properties of nanowires differing from the bulk characteristics.In our study, GaN nanowires are grown catalytically using either HVPE (Hydride Vapor Phase Epitaxy) or CVD (Chemical Vapor Deposition) method. After the growth electrical and optical characterizations are done on individual nanowires free of unwanted byproducts from the growth. Electron-beam lithography and photolithography are used to make metal contacts on individual GaN nanowires with various lengths and diameters. Resitivity is measured from room to cryogenic temperatures to illuminate the transport mechanism in GaN nanowires. Transconductance measurement is done in Field Effect Transistor (FET) device geometry to find carrier type, density, and mobility. The measurement shows our nanowires to be highly conductive and n-type regardless of the growth method. Challenges of lowering the unintentional doping level are discussed. An observed hysteretic behavior in transconductance measurement is reported and possible causes are discussed. Photoluminescence measurements are done on individual nanowires and results are discussed. TEM and STEM/EDS x-ray mappings are carried out to characterize the crystal structure and chemical makeup of nanowires.
5:30 PM - Q9.5
Fabrication of Horizontal GaN Nanowires and Interconnected Nanobridges for Sensing Applications.
Tania Henry 1 , Kyungkon Kim 1 , George Cui 1 , Jung Han 1 , Y. Song 2 , A. Nurmikko 2 , Hong Tang 3
1 Department of Electrical Engineering, Yale University, New Haven, Connecticut, United States, 2 Division of Engineering, Brown University, Providence, Rhode Island, United States, 3 Department of Physics, California Institue of Technology, Pasadena, California, United States
Show Abstract Nanowires are typically processed into nanodevices through solution dispersion and electrically accessed after contact metallization. This process presents inherent challenges in controlling the spatial ordering of final devices and avoiding contact resistance. We will demonstrate in this paper the feasibility of using crystallographic alignment of nanowire arrays, in conjunction with the concept of selective area growth, to achieve spatial alignment of nanowires with enhanced functionality. With the realization of horizontally aligned GaN nanowires, preliminary testing of their nanomechanical behavior has been conducted; high frequency resonance with a very high quality factor (Q~13,000) was observed. Crystallographic information forms the basis in designing and selecting an epitaxial system. The employment of multi-facetted GaN mesas enables a combinatorial survey of the tendency and selectivity of nanowire growth along the different planes. The Ni catalyst deposited rough GaN substrate was transferred to a CVD reactor. After the VLS growth, we observed hexagonally aligned horizontal nanowires from the c-plane and pyramidal m-plane of individual GaN mesas; TEM confirmed that the preferential nanowire growth direction is along the m-axis. In contemporary III-nitride research the use of epitaxial lateral overgrowth (ELO) is known to form well-defined stripes or hexagons bound by either prism or pyramidal m-planes, providing a natural and deterministic support for aligned nanowire growth. The integration of top-down lithographically-defined ELO patterning with bottom-up VLS synthesis enables precise control of the placement of nanowires and their spatial registry. The ELO mesas serve the dual purposes as 1) single-crystalline support for nanowire epitaxy, and 2) conducting electrodes that will facilitate carrier injection across the epitaxial, barrier-free interface. GaN ELO mesas in stripe and hexagon forms were prepared on insulating AlN epilayers. Horizontally aligned GaN nanowires, in comb-like arrays and/or hexagonal network of nanowires, interconnecting ELO mesas were observed with high spatial ordering. The density and diameter of the nanowires are correlated with the thickness of catalyst thin films (Ni). Preliminary results show that the GaN ELO mesas are conducting (resistivity~1e-4 ohm-cm) yet electrically insulated. Metal contacts defined by conventional photolithography are made to connect ELO mesas supporting nanowire arrays. Further measurement of contacted GaN nanowire bridges will be presented. The nanomechanical resonance of both connected GaN nanobridges (doubly clamped) and nanowire cantilever (singly clamped) was tested using optical scattering in a modified SEM setup. Preliminary data of both doubly and singly clamped nanowire reveal a very high quality factor (>13,000). Combination of ELO with nanowire synthesis is expected to provide a new paradigm for nano- electronic and electromechanical devices.
Q10: Poster Session: Nanotubes and Nanowires: Synthesis and Applications
Session Chairs
Prabhakar Bandaru
Morinobu Endo
Ian Kinloch
Apparao Rao
Wednesday AM, November 29, 2006
Exhibition Hall D (Hynes)
9:00 PM - Q10.1
Synthesis and Characterization of Pyrochlore-type Bi2Ti2O7 Nanotubes.
Hongjun Zhou 1 , Tae-Jin Park 1 , Stanislaus Wong 1 2
1 Chemistry, SUNY Stony Brook, Stony Brook, New York, United States, 2 , Brookhaven National Lab, Upton, New York, United States
Show Abstract9:00 PM - Q10.10
Mn-incorporated ZnSe and CdSe 1-dimensional Nanostructures.
Jinyoung Lee 1 , Dae Sung Kim 1 , Hye Jin Chun 1 , Ja Hee Kang 1 , Shin Young Kim 1 , Sang Won Yoon 1 , Jeunghee Park 1
1 Material Chemistry, Korea University, Seoul Korea (the Republic of)
Show Abstract9:00 PM - Q10.11
Synthesis of Pure Boron Single-Wall Nanotubes.
Dragos Ciuparu 2 1 , Mathieu Pinault 1 , Lisa Pfefferle 1
2 Department of Petroleum Processing and Petrochemistry, Petrol-Gaze University of Ploiesti, Ploiesti Romania, 1 Department of Chemical Engineering, Yale University, New Haven, Connecticut, United States
Show Abstract9:00 PM - Q10.12
Synthesis, Optical, and Magnetic Properties of Cd1-xMnxS Nanowires.
Dae Sung Kim 1 , JinYoung Lee 1 , Hye Jin Chun 1 , Jeunghee Park 1
1 , Korea University, Seoul Korea (the Republic of)
Show Abstract9:00 PM - Q10.13
HVPE and CVD Growth of InN Nanowires.
George Seryogin 1 , Ilan Shalish 1 , Venkatesh Narayanamurti 1 , Jiming Bao 1 , Federico Capasso 1
1 Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States
Show AbstractInN is one of the key components of group III nitride compound system, enabling bandgap engineering to cover the visible and infrared portions of the spectrum. Despite extensive efforts, InN growth remains very challenging. We report on hydride vapor phase epitaxy (HVPE) and chemical vapor deposition (CVD) growth of InN nanowires on Si and sapphire substrates. The wires were grown in a home-built HVPE and CVD systems in temperatures ranging from 500 to 600 C. InN is particularly difficult to grow by HVPE, because HCl gas is present in the process and tends to etch the formed InN. To avoid the HCl reaction, we used indium chlorides formed in a separate process step. To facilitate the vapor-liquid-solid (VLS) mode of growth, the substrates were predeposited with nickel catalyst. In the CVD growth, indium vapor and ammonia reacted directly. Gold or nickel were used as the catalyst and the InN growth was confined to catalyst deposited features.Regardless of the growth method, the low growth temperature of InN results in a low efficiency of ammonia decomposition and almost an order of magnitude longer growth process time as compared to GaN. The use of nickel as a catalyst is commonly believed to also catalyze ammonia decomposition. However, it is not clear whether the nickel particles indeed catalyze the VLS growth mechanism or rather promote the growth through the local enhancement of ammonia decomposition, as nickel is not unambiguously detected at the tip of the wire, as is commonly the case with gold. Scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS) show the structure and identify the wire elements. X-ray diffraction (XRD) was used to verify the crystalline structure and quality. The thickness of the wire ranged from 200 to 400 nm for HVPE and 100 to 200 nm for CVD. Photoluminescence shows a broad structure of several features ranging from 1000 to 1600 nm.
9:00 PM - Q10.14
Straightforward Synthesis of Single Crystalline Rutile TiO2 Nanowires.
Syed Amin 1 , Terry Xu 1
1 Department of Mechanical Engineering & Engineering Science, The University of North Carolina at Charlotte, Charlotte, North Carolina, United States
Show AbstractSingle crystalline rutile TiO2 nanowires were synthesized by direct heating of Ti(II)O powders in argon at 800-900 °C and 1 atmosphere in a tube furnace. The nanowires were of 20-40nm in diameter and several micrometers in length. These nanowires were characterized by a range of methods including scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and Raman spectroscopy. To explore the growth mechanisms, a series of control experiments including varying particle size, introducing catalytic materials, adjusting reaction pressure were performed. The possible growth mechanisms will be discussed. The optical properties of the nanowires were also studied and will be reported. The as-synthesized nanowires have potential applications in UV-protections, gases and humidity sensing, and others.
9:00 PM - Q10.15
Solution Based Semiconductor Nanowires.
Masaru Kuno 1 , Darren Peterson 1 , Vladimir Protasenko 1
1 Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States
Show Abstract9:00 PM - Q10.16
High Yield Growth of Amorphous Free CdS Nanowires, Nanobelts, and Turf-like Structure at Low Temperatures over a Quartz Substrate.
Juno Lawrance 1 , Lifeng Dong 2 , Josh Green 2 , Jun Jiao 2
1 Electrical and Computer Engineering, Portland State University, Portland, Oregon, United States, 2 Department Of Physics, Portland State University, Portland, Oregon, United States
Show Abstract9:00 PM - Q10.17
Growth of Gallium Nitride Nanowires and Nanospirals.
Goutam Koley 1 , Zhihua Cai 1
1 Electrical Engineering, University of South Carolina, Columbia, South Carolina, United States
Show Abstract9:00 PM - Q10.18
Ambient Template-directed Synthesis of Single-crystalline Alkaline Earth Metal Fluoride Nanowires.
Fen Zhang 1 , Yuanbing Mao 1 , Stanislaus Wong 1 2
1 Chemistry, State University of New York at Stony Brook, Stony Brook, New York, United States, 2 Materials and Chemical Sciences, Brookhaven National Laboratory, Upton, New York, United States
Show AbstractOne-dimensional nanostructures, such as nanowires, have attracted considerable attention because of their singular properties associated with quantum confinement and low-dimensionality, as well as their potential applications as building blocks for the assembly of nanoscale electronic, optoelectronic, and sensing devices. Fluorides have been widely used in optics and components in semiconductor-on-insulator structures. In addition, fluorides doped with rare-earth ions have also been reported to display unique luminescence properties. It is reasonable to expect that nanoscale fluorides will play an important role in technological applications including as high-density optical storage devices, nanosensors, and color displays. Herein, we demonstrate that a family of single-crystalline alkaline earth metal fluoride nanowires, as well as their rare-earth ion doped analogues, of varying controllable sizes can be successfully prepared using a modified template-directed method at ambient room temperature conditions, without the use of either sophisticated experimental setups or high-temperature annealing. Moreover, the diameters of the as-fabricated nanowires could be controlled by choosing commercially available, track-etch polycarbonate membranes with predictable pore sizes. Resulting nanowires have been extensively characterized by microscopy and spectroscopy data. The luminescent properties of lanthanide-doped binary fluoride nanowires imply the possible incorporation into nanoscale devices via a more thorough investigation of their optical and optoelectronic properties.
9:00 PM - Q10.19
Growth of Si Nanowires and Nanowire Arrays by Molecular Beam Epitaxy.
Peter Werner 1 , Alexey Milenin 1 , Nikolai Zakharov 1 , Ulrich Goesele 1
1 , MPI of Microstructure Physics, Halle (Saale) Germany
Show Abstract9:00 PM - Q10.2
Sonoelectrochemical Synthesis of Single Crystalline Semiconducting Copper Sulfide Nanowires.
Krishna Singh 1 , Alfredo Martinez 2 , Omar Yilmaz 2 , Mihri Ozkan 2
1 Chemical Engineering, UC Riverside, Riverside, California, United States, 2 Electrical Engineering, UC Riverside, Riverside, California, United States
Show Abstract9:00 PM - Q10.20
Vertically Aligned Growth of Sub-30 nm ZnO Nanowires Using Single-ion Nanolithography.
Daniel Baptista 1 2 , Sharvari Dalal 2 , Ricardo Papaleo 3 , Fernando Zawislak 1 , Paulo Fichtner 4 , Ken Teo 2 , Willian Milne 2
1 Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre Brazil, 2 Engineering Department, University of Cambridge, Cambridge United Kingdom, 3 Faculdade de Física, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre Brazil, 4 Departamento de Metalurgia, Universidade Federal do Rio Grande do Sul, Porto Alegre Brazil
Show AbstractWe report on large area growth of thin and aligned ZnO nanowires through the use of single ion nanolithography as a sub-30 nm patterning tool. The ZnO nanowires are grown in a tube furnace by evaporation of a ZnO:graphite mixture onto sapphire substrates patterned with Au catalyst. The substrate patterning was performed using random ion beam irradiation with Au ions at 20 MeV with a fluence range from 10^8 to 10^10 cm^-1. A thin PMMA film of 50 nm was spin coated on the sapphire substrates and then subjected to the ion irradiation. Although the substrate areas were approximately 1 cm^2, the irradiation covered an area of 5x5 cm in a fast scan of approximately 2 seconds. The low fluence range isolates the ion-sample interactions, reducing the probability of spatial superpositions. Each ion interacts individually with the PMMA film forming a cylindrical track of latent chemical damage, which is then developed using MBIK:IPA solution. After development and the evaporation of the Au catalyst, the PMMA film is removed by lift-off and small gold islands of 25 nm remain on the sapphire substrates. The irradiation fluence defines the mean distance between each island and therefore their density. Isolated ZnO wires with diameters of 25-28 nm were produced by the above method, which is not limited by the interdependence of pattern diameter and density typical of self assembling techniques and is much faster than e-beam lithography to draw sub-100 nm features over large areas.
9:00 PM - Q10.21
Fabrication of Small MgO Nanowires by Pulsed Laser Deposition.
Takeshi Yanagida 1 , Kazuki Nagashima 1 , Hidekazu Tanaka 1 , Tomoji Kawai 1
1 ISIR-Sanken, Osaka University, Osaka Japan
Show Abstract9:00 PM - Q10.22
Vanadium Dioxides Nanorods: From B Phase to M Phase.
Liqiang Mai 1 2 , Wangli Guo 1 , Tao Hu 1 , Wen Chen 1 , Wei Jin 1 , Bo Hu 1 , Ch.V.Subba Reddy 1
1 Institute of Materials Science and Engineering, Wuhan University of Technology, Wuhan, Hubei, China, 2 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show Abstract9:00 PM - Q10.23
Selective Patterning of Carbon Nanotube added V_2O_5 Nanowire Channel via BOE Treated PDMS Stamping Technique.
Yong-Kwan Kim 1 , So Jeong Park 2 , Gyu Tae Kim 2 , Jeong Sook Ha 1
1 Department of Chemical and Biological Engineering , Korea University, Seoul Korea (the Republic of), 2 Department of Electrical Engineering, Korea University, Seoul Korea (the Republic of)
Show AbstractPoly dimethylsilioxane (PDMS) has been widely used in various fabrication processes including soft lithography and MEMS, owing to its useful properties such as hydrophobicity, contamination resistance, and long-term endurance. The hydrophobicity and inertness of PDMS guaranteed the pattered thin film as an efficient passivation layer over reactive ion etching and atomic layer deposition process in a similar way as octadecyltrichlorosilane self-assembled monolayers (SAMs). In this study, we successfully fabricated carbon nanotube (CNT) added V_2O_5 nanowire channel patterns on the desired site of SiO_2 substrate by using transferred PDMS as an passivation layer. Various line and checker-board patterns of PDMS with a width of a few micrometers to 300 nm and a thickness of 30 nm could be transferred by stamping the BOE (buffered oxide etcher)-treated PDMS stamp on SiO_2 substrates for 5 minutes. In the similar way, we also manufactured the PDMS patterns on the -NH2 terminated SAM by printing of BOE treated PDMS stamp on 3-aminopropyl- triethoxysilane (APS) surfaces. This patterned surface of PDMS/APS was immersed into aqueous V_2O_5 nanowire solution for the selective adsorption of the nanowires onto APS area owing to attractive interaction between negatively charged V_2O_5 nanowires and the –NH_2 terminated APS SAM. Successively, the substrate was immersed into CNT solution for the additional adsorption of CNTs onto V_2O_5 patterns due to mutual attractive polar interaction between CNTs and V_2O_5 nanowires. As a result, we could make patterns of CNT added V_2O_5 nanowire channels on APS using transferred PDMS pattern as passivation layer. Electrical measurements showed that the conductivity of the CNT/V_2O_5 hybrid channel increased noticeably compared to that of the original V_2O_5 channel since the co-adsorbed CNTs worked as current bridges in the V_2O_5 nanowire channel. We suggest that the patterned CNT/V_2O_5 nanowire hybrid channel would enhance the sensitivity of V_2O_5 nanowires, which have relatively high electrical resistance, as functional devices such as chemical sensors.
9:00 PM - Q10.24
Growth Study of CVD Au Catalyzed Silicon Nanowires and Integration in an Organized Nanoporous Alumina Template.
Pascal Gentile 1 , Thomas David 1 , Denis Buttard 1 , Martien Den Hertog 1 , Jean-Luc Rouvière 1 , Pierre Ferret 2 , Florian Dhalluin 3 , Thierry Baron 3
1 DRFMC/SP2M, CEA, Grenoble France, 2 DRT/Leti/DOPT, CEA, Grenoble France, 3 LTM, CNRS, Grenoble France
Show Abstract9:00 PM - Q10.25
Laser Interference Lithography Tailored for Ordered Arranged ZnO Nanowire Arrays.
Dongsik Kim 1 , Hongjin Fan 1 , Ran Ji 1 , Roland Scholz 1 , Kornelius Nielsch 1 , Ulrich Goesele 1 , Margit Zacharias 2 1
1 Dep. II, MPI of Microstructure Physics, Halle Germany, 2 FWIM, FZ Rossendorf, Dresden Germany
Show Abstract9:00 PM - Q10.26
A Novel Technique to Synthesize Alumina Nanofibers/Nanotubes.
Anup Pancholi 1 , Copeland Kell 2 , Valeria Stoleru 1
1 Materials Science and Engineering, University of Delaware, Newark, Delaware, United States, 2 Chemical Engineering, University of Delaware, Newark, Delaware, United States
Show Abstract9:00 PM - Q10.27
Synthesis and Characterization of Branched Nanowire Heterostructures.
Yeonwoong Jung 1 , Dong-Kyun Ko 1 , Ritesh Agarwal 1
1 Materials Science & Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States
Show Abstract9:00 PM - Q10.28
III-V Nanowires Grown by Metal-organic Chemical Vapour Deposition for Optoelectronic Applications.
Yong Kim 1 , Hannah Joyce 1 , Qiang Gao 1 , Hoe Tan 1 , Chennupati Jagadish 1 , Mohanchand Paladugu 2 , Jin Zou 2
1 Electronic Materials Enginering, The Australian National University, Canberra, Australian Capital Territory, Australia, 2 Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland, Australia
Show Abstract9:00 PM - Q10.29
Metallothermic Synthesis of Nanowires and Related Nanostructures of Al2O3 and MgO.
Boris Bokhonov 1 , Mikhail Korchagin 1 , Yurii Yukhin 1
1 , Institute of solid state chemistry SB RAS, Novosibirsk Russian Federation
Show Abstract9:00 PM - Q10.3
The Effect of Manganese on VLS Growth of Germanium Nanowires.
Jessica Lensch 1 , Eric Hemesath 1 , Lincoln Lauhon 1
1 Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States
Show AbstractOne-dimensional semiconducting materials have shown considerable promise in electronic and optical applications. In order to introduce magnetic functionality into semiconductor nanowires, we have attempted to incorporate high concentrations of Mn atoms into Ge nanowires grown by the vapor-liquid-solid (VLS) mechanism. Ge nanowires were synthesized by the VLS mechanism in a hot wall chemical vapor deposition system using Au catalyst particles and GeH4 gas. During Ge nanowire growth, the Mn source tricarbonyl methylcyclopentadienyl manganese (TCMn) was introduced into the reactor using H2 as a carrier gas to produce molar ratios of 0.001-0.02 TCMn:GeH4. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the effects of varying TCMn concentrations on the morphology of the Ge nanowires. In the absence of TCMn, a high density of straight Ge nanowires could be grown, whereas low concentrations of TCMn resulted in branched nanowire structures. For molar ratios of 0.001-0.01 TCMn:GeH4, small branches grew from the primary nanowire, and the density increased with TCM concentration. Previously, TCMn was found to have a similar effect on InAs nanowire growth (May et al, Adv. Mater. 17, 598 (2005)), but for the present case the side branches were not as long nor as straight. At higher TCMn mole ratios (0.02), the catalyst became unstable, resulting in a disruption of unidirectional growth and highly curved and kinked nanowires. Branching was also observed. Analytical and high-resolution TEM studies are being undertaken to understand the role of Mn in the evolution of the Ge nanowire morphology, and to relate basic defect structures to the overall nanowire morphology. This investigation raises the more general question of how of high concentrations of impurities, intentional or otherwise, may affect the VLS growth of nanowires.
9:00 PM - Q10.30
Controlled Growth of GaN Nanowires by means of Chemical Vapor Deposition on Patterned Substrates.
Zhen Wu 1 , Yung Joon Jung 2 , Latika Menon 1
1 Physics, Northeastern University, Boston, Massachusetts, United States, 2 Mechanical Engineering, Northeastern University, Boston, Massachusetts, United States
Show Abstract9:00 PM - Q10.31
Large-Scale, Multifunctional, 2D and 3D Assemblies of Catalytic Nanowires.
Z. Ryan Tian 1 2 3 , Wenjun Dong 1 , Michelle McDonald 1 , Michael Jackson 1 , Andrew Cogbill 1 , Carmen Padilla 2
1 Chemistry/Biochemistry, University of Arkansas, Fayetteville, Arkansas, United States, 2 Cell and Molecular Biology, University of Arkansas, Fayetteville, Arkansas, United States, 3 Microelectronics and Photonics, University of Arkansas, Fayetteville, Arkansas, United States
Show Abstract9:00 PM - Q10.32
Position-controlled Formation of Quantum Dots and Nanowires at Iron Silicide Nanowires.
Zhenyu Liu 1 , Judith Yang 1 , Kyeongjae Cho 2
1 Department of Materials Sci. & Eng., University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 2 Department of Mechanical Engineering, Stanford University, Stanford, California, United States
Show Abstract9:00 PM - Q10.33
Ultranarrow Bi2S3 and Sb2S3 Nanowires.
Reihaneh Malakooti 1 , Ludovico Cademartiri 1 , Srebri Petrov 1 , Andrea Migliori 2 , Geoffrey Ozin 1
1 Department of Chemistry, University of Toronto, Toronto, Ontario, Canada, 2 , CNR-IMM, Bologna Italy
Show Abstract9:00 PM - Q10.35
Coaxial Homostructure Gallium Nitride Nanowires.
Benjamin Jacobs 1 , Virginia M. Ayres 1 , Martin A. Crimp 2 , Jiaming Zhang 2 , MaoQi He 3 , Joshua B. Halpern 3
1 Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan, United States, 2 Chemical Engineering & Materials Science, Michigan State University, East Lansing, Michigan, United States, 3 Department of Chemistry, Howard University, Washington, District of Columbia, United States
Show Abstract9:00 PM - Q10.36
Wafer Scale Fabrication of E-beam Written Suspended TiW Nanowires.
Lauge Gammelgaard 1 , Rudy Wojtecki 1 , Peter Bøggild 1
1 Department of Micro- and Nanotechnology, Technical University of Denmark, Lyngby Denmark
Show AbstractNanowires of various materials have shown a great potential as the sensing part in many different types of sensors, spanning as different areas as bio, chemical, electrical and mechanical sensors [1]. Therefore a large effort to make fundamental studies of nanowires and integrate these in microsystems is ongoing. In this work, we have realized wafer scale fabrication of arrays of suspended TiW nanowires with dimensions comparable to those of very long multi walled carbon nanotubes (50nm x 60nm x 8micron). The nanowires are fabricated by e-beam lithography and lift-off of a low-stress, sputtered TiW thin film, followed by a wet etch in BHF to remove the under laying 1 micron SiO2 layer. Initial studies indicate that stiction can be minimized by etching the oxide in HF vapours instead of performing a wet oxide etch, but for double clamped wires shorter than 10 micron no stiction problems are observed regardless of the oxide etch used. Since the dimensions of these wires can be easily tailored down to nanometer size using state-of-art e-beam lithography, the wires can for example be used to investigate how the mechanical properties scale with size [2]. AFM measurements has shown that the surface roughness of the TiW (10/90 w.t %) in an 10 x10 μm area is around 4-7 nm peak-to-valley, whereas electrical 4 point probe measurements on bond pads have shown a resistivity of around 40 µΩcm. Both of these properties seem to depend on the power and pressure during deposition. Among other important properties of the TiW material used for the wires are the high Young’s modulus of approximately 450 GPa, a non-oxidizing surface, extreme mechanical wear resistance, and a melting point well above 1670 degree, making them ideal for applications such as nanoresonators or heaters. Further studies are needed to assess whether these properties hold at the nanoscale. Finally, TiW is rather inert, and has a very low etch rate in most commonly used substances used in silicon micromashining processes such as; BHF, HF, KOH, Phosphoric acid, Acetone, IPA, 7-up etc (below 1 nm/min, slightly higher for KOH though). Only Piranha seems to etch the TiW with 20 nm/min. All in all, we expect wafer scale TiW nanowire fabrication to be a fast and easy route to a highly versatile NEMS system. References[1] M. S. Gudiksen, L. J. Lauhon, J. Wang, D. C. Smith and C. M. Lieber, Nature 415, 617-620 (7 February 2002)[2] B. Wu, A. Heidelberg, J. J. Boland, Nature Materials 4, 525-529 (Jul 2005) Letters
9:00 PM - Q10.37
Carrier Doping of Silicon Nanowires Synthesized by Laser Ablation.
Naoki Fukata 1 3 , Naoya Okada 2 , Satoshi Matsushita 2 , Takao Tsurui 4 , Jun Chen 1 , Takashi Sekiguchi 1 , Noriyuki Uchida 2 3 , Kouichi Murakami 2 3
1 , Advanced Electronic Materials Center, National Institute for Materials Science, Tsukuba Japan, 3 , Special Research Project on Nanoscience, University of Tsukuba, Tsukuba Japan, 2 , Institute of Applied Physics, University of Tsukuba, Tsukuba Japan, 4 , Institute for Materials Reseach, Tohoku University, Sendai Japan
Show AbstractOne-dimensional silicon nanowires (SiNWs) are of great interest in the fields of both fundamental and application research. Various demonstrations have been reported for future application of SiNWs such as electronic and optical devices. To realize such devices, the characterization and impurity-doping of SiNWs are of important subjects. Raman scattering measurements are sensitive for Si optical phonon, which gives valuable information about crystallinity, stress, and diameter of SiNWs. The bonding structures and the site of dopant atoms in SiNWs can be also investigated by Raman scattering measurements. Electron spin resonance (ESR) measurements are also sensitive for defects and electronic states of dopant atoms. In the present study, we synthesized boron (B)- or phosphorus (P)-doped SiNWs by laser ablation and investigated the site, bonding structures, and electronic structures of dopant atoms in them by Raman and ESR measurements.SiNWs were synthesized by laser ablation of a Si target with nickel as a metal catalyst [1] and B or P as dopant impurities which was placed in a quartz tube heated at 1473 K in a flowing Ar gas. The growth mechanism of SiNWs is VLS (Vapor-Liquid-Solid) growth. Micro-Raman scattering measurements were performed at room temperature (RT) with a 100x objective and a 532-nm excitation light at a power of 0.02 mW to avoid the local heating effect due to the excitation laser. ESR measurements were carried out at 4.2 K using an X-band ESR spectrometer with a magnetic field modulation of 100 kHz.A Raman peak was observed at about 618 cm-1 for SiNWs synthesized by using a target with B dopant. The peak frequency is in good agreement with that of a local vibrational mode of B in Si crystal. The Fano broadening due to a coupling between the discrete optical phonon and a continuum of interband hole excitations was also observed in the optical phonon peak, which indicates heavily B doping during VLS growth. These results prove that B atoms were doped in substitutional sites of Si in SiNWs. ESR measurements were also performed to investigate defects and P donor/conduction electrons in SiNWs. An ESR signal due to conduction electrons were observed for SiNWs synthesized by using a target with P, suggesting that P atoms were doped in SiNWs. Several signals related to defects were also observed. The results show that it is necessary to reduce or passivate them for the realization of nano-devices using SiNWs.[1] N. Fukata, T. Oshima, K. Murakami, T. Kizuka, T. Tsurui, and S. Ito, Appl. Phys. Lett. 86, 213112 (2005).
9:00 PM - Q10.38
Large Scale Hierarchical Organization of Nanowires for Integrated Nanosystems
Mathias Steinmair 1 , Erwin Auer 1 , Alois Lugstein 1 , Christoph Schöndorfer 1 , Emmerich Bertagnolli 1
1 Institute of Solid State Electronics, TU Vienna, Vienna Austria
Show Abstract9:00 PM - Q10.39
ALD Synthesis of Metal and Metal Oxide Nanotubes in AL2O3 Membranes.
Kornelius Nielsch 1 , Mato Knez 1 , Mihaela Daub 1 , Ulrich Gösele 1
1 , Max Planck Institute of Microstructure Physics, Halle Germany
Show Abstract9:00 PM - Q10.4
General Synthesis and Properties of Novel Transition Metal Silicide Nanowires.
Andrew Schmitt 1 , Lei Zhu 1 , Song Jin 1
1 Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States
Show Abstract9:00 PM - Q10.41
High Performance and Durability of AFM Tips Based on a Carbon-carbon (a-C, CNT) Composite.
Denise Nakabayashi 1 2 , Alberto Moreau 1 , Paulo Silva 2 , Vitor Coluci 1 , Douglas Galvão 1 , Monica Cotta 1 , Daniel Ugarte 1 2
1 Física Aplicada, IFGW-UNICAMP, Campinas, SP, Brazil, 2 Lab. Microscopia Eletrônica, Lab. Nac. Luz Síncrotron, Campinas, SP, Brazil
Show Abstract9:00 PM - Q10.42
Engineering Carbon Nanotube Atomic Force Microscopy Nanoprobes.
Haoyan Wei 1 , Sang Nyon Kim 2 , Minhua Zhao 1 , Sang-Yong Ju 2 , Bryan Huey 1 , Fotios Papadimitrakopoulos 2 , Harris Marcus 1
1 Materials Science and Engineering Program, Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, Connecticut, United States, 2 Nanomaterials Optoelectronics Laboratory, Polymer Program, Institute of Materials Science, Department of Chemistry, University of Connecticut, Storrs, Connecticut, United States
Show AbstractCarbon nanotubes (CNTs) were assembled onto conductive atomic force microscopy (AFM) probes using dielectrophoresis (DEP). This process involved the application of a 10V, 2 MHz, AC bias between a metal-coated AFM probe and a dilute suspension of single-wall carbon nanotubes (SWNTs). The high electric field exerted at the tip of these AFM probes (positive dielectrophoresis) aligned the nanotubes and caused them to precipitate out of their suspension and onto the probe. The gradual displacement of the AFM probe away from the SWNT suspension consolidated nanotubes into nanofibrils with a high degree of alignment as demonstrated with polarization Raman experiments. By varying the pulling speed, immersion time and concentration of the CNT suspension, one can tailor the diameter of these probes, and according to nanomechanical measurements also their corresponding stiffness. Precise length trimming of these nanofibrils was demonstrated by their partial re-immersion into a liquid that strongly interacted with the exposed precipitated nanotubes, such as sodium dodecyl sulfate (SDS) solution. Such dissolution was feasible because SDS micellarized SWNTs and re-dispersed them. Vacuum annealing these nanoprobes at temperature up to 450°C further increased their stiffness and rendered them insoluble to SDS and all other aqueous media. Finally, re-growth of a new CNT fibril on top or at the end of a previously grown nanoprobe was also demonstrated by re-immersing the previously grown fibril to the desired depth in a new CNT suspension and repeating the dielectrophoretic assembly. The resulting high-aspect-ratio CNT AFM probes have been tested and proven electrically conductive and mechanically robust to be used as mechanical nano-needles and electrochemical nanoprobes.
9:00 PM - Q10.43
Single-Walled Carbon Nanotube Tip for Scanning Tunneling Microscope.
Winadda Wongwiriyapan 1 , Takafumi Ohmori 1 , Yuya Murata 1 , Kenji Motoyoshi 1 , Hirofumi Konishi 1 , Masaru Kishida 1 , Kenji Kisoda 2 , Hiroshi Harima 3 , Jung-Goo Lee 4 , Hirotaro Mori 4 , Shin-ichi Honda 1 , Mitsuhiro Katayama 1
1 Electrical, Electronic and Information Engineering, Osaka University, Osaka Japan, 2 , Wakayama University, Wakayama Japan, 3 , Kyoto Institute of Technology, Kyoto Japan, 4 Research Center for Ultrahigh Voltage Electron Microscopy, Osaka University, Osaka Japan
Show Abstract9:00 PM - Q10.44
Carbon Nanotubes (CNTs) Characterization and Quality Control.
Mohammad Al-khedher 1 , Chuck Pezeshki 1 , Jeanne McHale 2
1 School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington, United States, 2 Department of Chemistry, Washington State University, Pullman, Washington, United States
Show AbstractIn order to commercialize carbon nanotube technology, advances must be made in production of nanotubes. One of the major obstacles for successful mass-production that have been identified is performing quick and precise characterization of the properties of a given batch of nanotubes. In this research, we have identified a set of intermediate steps that will lead to the goal of a comprehensive, scalable set of procedures for analyzing nanotubes. The proposed methodology is originated with data processing for Raman spectrum of CNT turfs and image analysis of SEM images. The morphology of CNT structure is extracted using image processing techniques of SEM images and the sample structural properties (i.e. CNTs alignment, curvature, thickness and orientation) are estimated using Artificial Neural Networks (ANN) classifier. The mechanical properties of CNT specimens will be characterized along with a Raman spectroscopy study. The correlation between the mechanical behavior of Multi-Wall carbon nanotubes (MWNTs) turfs, Raman spectra of CNTs and the morphology of the turf structure will be investigated through the use of Adaptive Neuro-Fuzzy Artificial phenomenological modeling. This system is built to model and estimate CNTs mechanical properties based on Raman spectroscopy, morphology information extracted from SEM images using image analysis, and nano-indentation results. This research will open the doors to understand CNT turfs mechanical behavior and relate it to the morphology of the structure. We believe this novel methodology, relating the material physical behavior with the structure morphology, will ultimately improve our capability to control the quality of the produced nanotubes through the supervised growth of CNTs and studying the InSitu nucleation of the turf. This scalable process will dramatically improve nanotubes design, the use of CNTs in Nanotechnology and MEMS, and it will facilitate full scale production.
9:00 PM - Q10.46
Organic Doped Carbon Nanotube: Structural, Electronic and Transport Properties.
Rodion Belosludov 1 , Amir Farajian 2 3 , Sang Lee 3 , Hiroshi Mizuseki 3 , Taishi Takenobu 3 , Yoshihiro Iwasa 3 , Yoshiyuki Kawazoe 1 3
1 ARCMG, Institute for Materials Research, Tohoku University, Sendai, Miyagi, Japan, 2 Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas, United States, 3 Institute for Materials Research, Tohoku University, Sendai, Miyagi, Japan
Show Abstract9:00 PM - Q10.47
Development of Multi Walled Carbon Nanotube p-n Junction Arrays via Micro Contact Printing.
Yamini Yadav 1 , Prasanna Padigi 1 , Xiaoyu Song 1 , Shalini Prasad 1
1 Electical Engineering, Portland State University, Portland , Oregon, United States
Show Abstract9:00 PM - Q10.48
Low Resistance Ohmic Contact Formation Mechanism for Carbon Nanotube Via Determined by Hard X-ray Photoemission Spectroscopy.
Daiyu Kondo 1 2 , Mizuhisa Nihei 1 2 , Shintaro Sato 1 2 , Akira Kawabata 1 2 , E. Ikenaga 3 , M. Kobata 3 , J. Kim 3 , K. Kobayashi 3 , S. Komiya 3 , Yuji Awano 1 2
1 Nanotechnology Research Center, Fujitsu Laboratories Ltd., Atsugi Japan, 2 , Fujitsu Limited, Atsugi Japan, 3 , Japan Syncrotron Radiation Research Institute/SPring-8, Hyogo Japan
Show AbstractCarbon nanotubes (CNTs) have been expected for use as wiring materials to solve a several problems in future ULSI interconnects. Recently, we have succeeded in forming CNT via whose resistance was in the same order as that of W plugs [1,2]. To improve via resistance, we have investigated the electronic structures at the interface between CNTs and metal electrodes using by hard x-ray photoemission spectroscopy (PES). The PES measurements were performed at the BL47XU in the SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI). We measured Ti 2p core-level spectra after CVD growth of CNTs of the following three sample structures: (a) Co 1-nm/Ti 2-nm film, (b) Co 2.5-nm/Ti 6-nm film and (c) as-deposited 4.5-nm Co particles/TiN 5-nm film on a silicon substrate. The growth temperature was 450-510°C. As the carbon source, a mixture of acetylene and argon gases was used. The resistance of 2 µm-diameter-via was about 1MΩ, 0.7Ω [1] and 0.59Ω [2], respectively. In the spectra (b) and (c), it has been found one feature originated from the titanium carbide (TiC) and titanium nitride (TiN), respectively. On the other hand, only a titanium oxide layer was observed in the sample (a), resulting in the high resistance. These results indicate that the existence of TiC or TiN contact layers should be important to realize such a low resistance CNT vias. Acknowledgement: The authors thank Dr. N. Yokoyama of Fujitsu Laboratories Ltd. for their support and useful suggestions. This work was supported by the Advanced Nanocarbon Application Project, which was consigned to JFCC by New Energy and Industrial Technology Development Organization (NEDO) of Japan. References:[1] M. Nihei et al., IITC 2005. [2] S. Sato et al., IITC 2006.
9:00 PM - Q10.5
A Novel Growth Method of Single-Crystalline Bi Nanowires.
Wooyoung Shim 1 , Jinhee Ham 1 , Kyoung-il Lee 1 , Joonyeon Chang 2 , Sukhee Han 2 , Wonyoung Jeoung 2 , Mark Johnson 3 , Wooyoung Lee 1
1 Department of Materials Science and Engineering , Yonsei University , Seoul Korea (the Republic of), 2 , Korea Institute of Science and Technology, Seoul Korea (the Republic of), 3 , Naval Research Laboratory, Washington, District of Columbia, United States
Show Abstract9:00 PM - Q10.50
Improvement of X-ray Current Density Using CNT Cold Cathode.
Choi Haeyoung 1 , Won Suk Chang 1 , Joung-uk Kim 1
1 Applied Imaging Research Group, Korea Electrotechnology Research Institute, Sa-1dong, Sangrok-gu, Ansan-shi, Gyeonggi-do Korea (the Republic of)
Show Abstract9:00 PM - Q10.51
Controlled Carbon Nanotube Networks and its Corresponding Channel Effect at High Bias.
Jun Huang 1 , Harindra Vedala 1 , Bangalore Rao 1 , Do-Hyun Kim 1 , WonBong Choi 1
1 Mechanical and Materials Engineering, Florida International University, Miami, Florida, United States
Show Abstract9:00 PM - Q10.52
Ultra-Large-Scale Fabrication of Individually Contacted Single-Wall Carbon Nanotube Devices by A/C-Dielectrophoretic Deposition.
Aravind Vijayaraghavan 1 , Matti Oron-Carl 1 , Simone Dehm 1 , Frank Hennrich 1 , Horst Hahn 1 , Ralph Krupke 1
1 Institut für Nanotechnologie, Forschungszentrum Karlsruhe, Karlsruhe Germany
Show AbstractSingle-Wall Carbon Nanotube (SWNT) devices are conventionally fabricated either by e-beam lithography or focused ion beam fabrication of metal contacts on randomly grown nanotubes, or the deposition of nanotubes from suspension randomly on a predefined array of electrodes. Both these approaches are tedious and results in very low yields and poor reproducibility. The recent demonstration of A/C-Dielectrophoretic deposition of SWNTs on prefabricated electrodes [1,2] provides the best possibility yet for scaled-up fabrication of a large number of SWNT devices.En-route to achieving this goal, we will explore a number of parameters that govern the deposition. These include conductivity and pH of the suspension; electrode design, density and spacing; deposition voltage and frequency; and the extent of capacitive coupling between the electrodes and the substrate. We will also present a model of the entire system as a network of competing impedances and discuss the regimes of the deposition in terms of these impedances. We will also discuss an equivalent picture in terms of electric field lines and gradients. Interestingly, this analysis and model is not specifically limited to SWNTs, and can be used to explore similar fabrication of other nanotube and nanowire devices. Having optimized all the parameters, we will present the successful fabrication of large parallel arrays of individually contacted SWNT devices on a single chip, with numbers exceeding tens of thousands of such devices per square centimeter, which is orders of magnitude greater then anything that is possible with other techniques. These arrays can be fabricated in a single, short, deposition step. The nanotubes in these devices enjoy the advantage of being contacted all around with metal using a two-step lithography process, to ensure minimum contact resistance. Additionally, by tuning the deposition condition, it also provides the possibility of making entire such arrays of only metallic nanotube devices, or a mixture containing predominantly semiconducting nanotube devices. This can be viewed as the first clear sign that it is in fact possible to successfully integrate SWNTs as transistors or interconnects in practically large numbers, as a part of existing silicon-based device architectures.(1) Krupke, R.; Hennrich, F.; Lohneysen, H. v.; Kappes, M. M.; Science, 2003, 301, 344-347.(2) Krupke, R.; Hennrich, F.; Weber, H. B.; Beckmann, D.; Hampe, O.; Malik, S.; Kappes, M. M.; Lohneysen, H. v.; App. Phys. A, 2003, 76, 397-400.
9:00 PM - Q10.53
Fabrication of Multi-Intramolecular Junctions Array of Single-Walled Carbon Nanotubes on Surface by Temperature Oscillated CVD.
Jin Zhang 1 , Yagang Yao 1 , Zhongfan Liu 1
1 College of Chemistry and Molecular Engineering, Peking University, Beijing China
Show AbstractSince the discovery of carbon nanotube in 1991, it was regarded as an ideal building block for nanoelectronics device, because they can function both as device and as the wire[1-2]. However, the use of nanotubes as building blocks is limited, because the selective controlled growth of semi-conducting or metallic nanotubes is not currently possible. The ideal building blocks for nanoelectronics device will require its electronic properties and structures should be defined and controlled. Recently, many efforts have been made to fabricate nanojunction as building blocks for nanoelectronics devices, such as intermolecular metal-semiconductor nanojunction and nanotube crossed nanojunction. However, the controlled growth of this sort of nanojunctions is still in its infancy. In the present work, multi-intramolecular junctions array of single-walled carbon nanotubes (SWCNTs) has been fabricated by temperature oscillated chemical vapor deposition (CVD). Micro-resonance Raman spectroscopy was used to detect the metallic-metallic, metallic-semiconductor and semiconductor-semiconductor SWCNTs junctions.References:1.H. W. C. Postma, T. Teepen, Z. Yao, M. Grifoni, C. Dekker, Science, 293, 76, 20012.P. G. Collins, A. Zettl, H. Bando, A. Thess, R. E. Smalley, Science, 278, 100, 1997.
9:00 PM - Q10.54
First-Principles Electronic Properties of Graphene Nanostrips.
John Mintmire 1 , Junwen Li 1 , Carter White 2
1 Department of Physics, Oklahoma State University, Stillwater, Oklahoma, United States, 2 Code 6189, Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractThe electronic structure of graphene nanostrips with zigzag edges is known to exhibit localized edge states in the vicinity of the Fermi level, with work by Fujita and others suggesting the possibility of ferrimagnetic behavior of these edge states. We present first-principles results for zigzag-edge graphene nanostrips including both closed shell and ferrimagnetic states as a function of width and substituent. Within the mean-field approach used, we find that the ferrimagnetic states examined are lower in energy than the closed shell states. We also discuss the implications of the first-principles band structures on empirical Hamiltonians. This work was supported by the DoD HPCMO CHSSI program through the Naval Research Laboratory.
9:00 PM - Q10.55
Geometry Dependent Resistivity in Single-walled Carbon Nanotube Films Patterned Down to Submicron Dimensions.
Ashkan Behnam 1 , Leila Noriega 1 , Yongho Choi 1 , Zhuangchun Wu 2 , Andrew Rinzler 2 , Ant Ural 1
1 Electrical & Computer Engineering , University of Florida, Gainesville, Florida, United States, 2 Physics, University of Florida, Gainesville, Florida, United States
Show AbstractSingle-walled carbon nanotubes (SWNTs) have attracted significant research attention in the last decade because of their remarkable physical and electronic properties, such as high mobility and current density. Despite these outstanding properties, however, controlling the diameter, chirality, location, and direction of individual nanotubes has proven very challenging. Recently, there has been a growing interest in using 2D nanotube networks and 3D nanotube films as a new class of materials, in which individual variations in diameter and chirality are ensemble averaged to yield uniform physical and electronic properties. Several applications of SWNT networks and films have recently been demonstrated, such as thin film transistors, flexible electronics, sensors, and transparent and conductive electrodes for optoelectronics. All of these potential applications require patterning of the nanotube films and understanding their electrical properties as a function of device geometry. Although 2D nanotube networks have been patterned recently by a variety of techniques, reproducible patterning of thicker nanotube films, particularly down to sub-micron linewidths, has not been demonstrated previously. Furthermore, how electrical properties of nanotube films scale as a function of device geometry, particularly device width, at submicron dimensions remains unexplored. In this talk, we demonstrate patterning of SWNT films down to 200 nm lateral dimensions using e-beam lithography and reactive ion etching with good selectivity and directionality. We then use this etch capability to fabricate standard four-point-probe structures to characterize the resistivity of these films as a function of device geometry. The resistivity of nanotube films are found to be independent of device length for a given width and thickness, while increasing over three orders of magnitude compared to bulk films, as the width and the thickness of the films shrink. In particular, we find that the resistivity of SWNT films starts to increase with decreasing device width below 20 μm, exhibiting an inverse power law dependence on device width at sub-micron dimensions with a critical exponent of about 1.5. We show that this behavior can be explained by a purely geometrical argument.The “top-down” patterning of these transparent, conductive nanotube films allows for their use in sub-micron device structures, and perhaps for their integration into standard silicon microfabrication technology. However, since the resistivity of very thin and narrow SWNT lines is over three orders of magnitude greater than that for thick and wide films, the resistivity scaling is an important effect that needs to be taken into account when fabricating small devices in which nanotube film transport characteristics play a vital role.
9:00 PM - Q10.56
Contact Transfer of Aligned Carbon Nanotube Arrays onto Conducting Substrates: Low temperature Process for Electronic Applications.
Ashavani Kumar 1 , Rajashree Baskaran 2 , Victor Pushparaj 1 , Swastik Kar 1 , Omkaram Nalamasu 1 , Pulickel Ajayan 1
1 Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States, 2 Components Research, Intel Corporation, Chandler, Arizona, United States
Show Abstract9:00 PM - Q10.57
Patterning Carbon Nanotube Mat Transistors using Transfer-Printing.
Vinod Sangwan 1 2 , Dan Hines 1 2 , Vincent Ballarotto 2 , Gokhan Esen 1 , Michael Fuhrer 1 , Ellen Williams 1 2
1 Physics, University of Maryland, College Park, Maryland, United States, 2 , Laboratory for Physical Sciences , College Park, Maryland, United States
Show Abstract9:00 PM - Q10.58
Enhancement of Field Emission of Aligned Carbon Nanotubes by Thermal Oxidation.
Baoqing Zeng 1 2 , Guangyong Xiong 1 , Shuo Chen 1 , WenZhong Wang 1 , Dezhi Wang 1 , Zhifeng Ren 1
1 Department of Physics, Boston College, Chestnut Hill, Massachusetts, United States, 2 School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu China
Show Abstract9:00 PM - Q10.60
An Electrically-tunable Ultra Small Liquid Crystal Micro-lens Array based on the Carbon Nanotubes
Xiaozhi Wang 1 , Xin Ji 1 , Timothy Wilkinson 1 , Ian Bu 1 , Kenneth Teo 1 , William Milne 1
1 Center for Advanced Photonics and Electronics, Dept. of Engineering, University of Cambridge, Cambridge United Kingdom
Show Abstract9:00 PM - Q10.61
Directed Linking of Carbon Nanotubes with Single CdSe Quantum Dots.
Kathryn Leach 1 , Todd Krauss 1
1 Chemistry, University of Rochester, Rochester, New York, United States
Show AbstractAs circuit miniaturization continues, the demand for smaller and more efficient component parts has increased. Metallic single-walled carbon nanotubes (SWNTs) are the ideal nanometer-scale wire, as they can withstand current densities up to 2 to 3 orders of magnitude higher than copper currently used in electronic chips. These conductive nanotubes can therefore be utilized as “nano-electrodes” to efficiently electrically contact another nanoscale object, such as a single semiconductor quantum dot (QD), thus creating macroscopic integrated systems based on nanometer-scale components. Although semiconductor QDs have been previously attached to NTs, the attachment scheme was uncontrolled; direct and defined attachment of QDs to SWNTs remains elusive.
We have designed a strategy for directed assembly of fabricated QD–SWNT devices. NTs were grown across patterned catalyst islands on a silicon wafer followed by electrode deposition. NTs spanning pairs of electrodes have been cut in half (leaving nanometer scale gaps) by applying voltage pulses to a metal-coated atomic force microscope (AFM) tip in very close proximity to a grounded nanotube. The resulting carboxylic group moieties found at the cut NT edges were used to covalently attach CdSe QDs with amine-terminated surface ligands using standard bioconjugation techniques. Electrostatic force microscopy (EFM) was used to monitor NT conductivity before and after cutting, as well as after QD attachment. The photoelectrical transport properties of a typical hybrid QD–SWNT device will be discussed.
9:00 PM - Q10.62
Influence of chemical dopant technique to reduce Schottky barriers of Pd-contacted CNTFETs
Damian Casterman 1 , Maria De Souza 1
1 Emerging Technologies Research Centre, De Montfort University, Leicester United Kingdom
Show AbstractPd-contacted devices have been shown to produce both ohmic as well as Schottky contacts in CNTs [1,2]. In particular, the variation of the Schottky barrier height depending upon processing conditions hampers the commercial viability of the technology. Pd has the ability to adsorb various types of atoms, leading to complexities which require to be well understood [3]. IBM research recently demonstrated subthreshold slopes of about 70mV/dec using Hexachloroantimonate, SbCl6-, in regions near Pd/CNT contacts [1]. In this work, ab initio investigations of the effect of SbCl6- on both a (8,0)-semiconducting carbon nanotube and a (100)-Palladium contact are reported for two situations (A) – Interaction of SbCl6- with (100)-Pd surface (B) – Interaction of SbCl6- with CNT Methodology:The ab initio calculations have been carried out using Density Functional Theory (DFT) implemented in Vienna Ab initio Simulation Package (VASP) within the Local Density Approximation (LDA). Ultra Soft pseudo-potential were used with plane wave method. Monkhorst-Pack mesh of (4x4x4) for Pd and (1x1x15) for CNT were used for integration of Brillouin zone. Cut-off energies were 219 eV for Pd and 358 eV for CNT.Results:A – SbCl6- is placed above a hollow site of a (100)-Pd surface. One Cl adsorption modifies the electronic properties of Pd surface due to charge transfer from Pd to Cl and leaves a neutral rehybridized SbCl5 close to surface. Our calculation reveals a potential lowering localized at interface which consequently reduces Schottky barrier height for holes.B - SbCl6- relaxed above a 6-hexagonal-ring of two unit cells of a (8,0) zigzag CNT. Charge transfer from CNT to SbCl6- degeneratly p-dopes the semiconducting nanotube by shifting down the Fermi level into the valence band. The averaged local potential variation is just less than half-midgap. Conclusion:Interactions between SbCl6- with CNT as well as Pd favours injection of majority carriers leading to better electronic properties. This work gives numerical insight into the influence of the charge transfer technique on Schottky barrier heights using ab initio pseudopotential theory.References: [1] Self-aligned carbon nanotube transistors with charge transfer doping, J. Chen, C. Klinke, A. Afzali and Ph. Avouris, Condensed Matter, Vol. 1, 0511039, November 2005.[2] Ballistic carbon nanotube field-effect transistors, Ali Javey et al., Nature (London), Vol. 424, p 654-657, August 2003.[3] Effect of hydrogen on the surface relaxation of Pd(100), Rh(100), and Ag(100), S. C. Jung and M. H. Kang, Phys. Rev. B 72, 205419, 2005.
9:00 PM - Q10.7
Molecular Beam Epitaxy III-V Nanowires by Using Group III Metals as a Catalyst.
Dance Spirkoska 1 , Emanuele Uccelli 1 , Max Bichler 1 , Gerhard Abstreiter 1 , Anna Fontcuberta i Morral 1
1 Walter Schottky Institut , Technische Universität München, Garching Germany
Show Abstract9:00 PM - Q10.8
Synthesis of Single-walled Carbon Nanotubes on Silicon Nanowires.
Hideto Yoshida 1 , Tetsuya Uchiyama 1 , Jun Kikkawa 2 , Seiji Takeda 1 3 , Yoshikazu Homma 4 3
1 Graduate School of Science, Osaka University, Osaka Japan, 2 Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology (AIST), Osaka Japan, 3 , CREST, JST, Saitama Japan, 4 Department of Physics, Tokyo University of Science, Tokyo Japan
Show Abstract Single-walled carbon nanotubes (SWNTs) and semiconductor nanowires have many extraordinary properties to impact future science and applications. Moreover, a junction structure of them is a potential nanomaterial as a Schottky diode and a light emitting diode. Therefore, we have synthesized SWNTs on silicon nanowires (SiNWs). We synthesized SiNWs by chemical vapor deposition as in the previous studies [J. Kikkawa et al., Appl. Phys. Lett. 86 (2005) 123109]. Au thin film about 1.0 nm thick was deposited on a Si substrate. The substrate was transfered to a quartz reaction tube set in a furnace, and then annealed at 773 K for 30 minutes. After that, monosilane gas, which was diluted to 1 % in Ar, was introduced into the quartz reaction tube at a flow rate of 1500 sccm and the pressure in the quartz reaction tube was kept at 98 kPa for 5 minutes. Consequently, SiNWs were synthesized on the substrate. SiNWs were dispersed in ethanol, and then the suspension containing SiNWs was deposited on a micro grid with a carbon supporting film. Next, for the SWNTs growth, Co thin film about 0.1 nm thick was deposited on the micro grid with SiNWs. The micro grid with SiNWs was placed in a quartz reaction tube set in a furnace and heated to 1073 K in Ar gas at a flow rate of 100 sccm with the pressure of about 5 kPa. After the temperature reached 1073 K, the Ar gas flow was replaced by ethanol gas as a carbon source at a flow rate of 150 sccm. The pressure in the quartz reaction tube was kept at about 5 kPa for 10 minutes. After growth, we observed an as-grown sample by means of a TEM. Many SWNTs are grown on SiNWs. In other words, heterostructures of SWNTs and SiNWs are synthesized. Among them, we could observed SWNTs with a catalyst nanoparticle at the root. The size relationship between catalyst nanoparticles and SWNTs has been investigated. We have also examined the role of surface oxide layer of SiNWs in SWNT growth. The detail of results will be presented at the congress.
9:00 PM - Q10.9
A Novel Tin-rich Phase of the Sn-O System Observed at Layered Nanobelts.
Marcelo Orlandi 1 , Matti Mäki-Jaskari 2 , Elson Longo 3 4 , Edson Leite 4
1 Department of Physics and Chemistry, São Paulo State University - UNESP, Ilha Solteira, São Paulo, Brazil, 2 Institute of Physics, Tampere University of Technology, Tampere Finland, 3 Institute of Chemistry, São Paulo State University, Araraquara, São Paulo, Brazil, 4 Department of Chemistry, Federal University of São Carlos, São Carlos, São Paulo, Brazil
Show AbstractTin oxide is an interesting material due to its unique properties, and the growth of tin oxide nanostructures was reported using several approaches. However, the stabilization of nonstoichiometric phases is still a challenge. In this work we present the growth of tin oxide nanobelts on a novel tin-rich phase. The synthesis was employed by a controlled carbothermal reduction process in a tube furnace, and the results show that this growth method should be a key for stabilization of this novel phase. The collected material was characterized by X-ray diffraction (XRD), Rietveld refinements, field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM) and energy disperssive X-ray spectroscopy (EDX). The results showed that the material is composed by nanobelts with layered growth, and by the Rietvetd refinements of X-ray data as found that the belts grow in a triclinic (P-1) structure with cell parameters a = 4.63 Å, b = 8.22 Å, c = 4.04 Å, α = 90.6°, β = 113.2° and γ = 96.1°. HRTEM results showed that epitaxial growth occurs between the layers and the belts have low concentration of defects. By semi-quantitative EDX analysis it was found that belts grow up in a tin-rich phase, with a stoichiometry close to Sn4O2. First principles theoretical calculations showed that tin-rich phases can be relatively stable in tin oxide crystals if layered growth occurs, which is in agreement with the experimental results. A growth mechanism of the nanobelts is proposed based on crystallization from vapor phase, in which the kinetics aspects of growth and the atmosphere of synthesis are fundamental to stabilize the layered and tin-rich nanobelts.
Symposium Organizers
Prabhakar Bandaru University of California-San Diego
Morinobu Endo Shinshu University
Ian Kinloch University of Cambridge
Apparao M. Rao Clemson University
Q11: Inorganic and Oxide Based Nanowires
Session Chairs
Wednesday AM, November 29, 2006
Room 312 (Hynes)
9:00 AM - **Q11.1
Inorganic Nanotubes and Fullerene-like Structures (IF): A Progress Report.
Reshef Tenne 1
1 Materials and Interfaces, Weizmann Institute, Rehovot Israel
Show AbstractIn this presentation a progress report, focused mainly on the results obtained in our lab will be presented. While the synthesis and study of IF materials from layered metal dichalcogenides, like WS2 and MoS2 remain a major challenge, some progress with the synthesis of IF structures from other compounds, like metal oxides and metal halides have been realized. The synthesis of some new IF materials, like Cs2O, NiBr2 and others will be described. The study of the mechanical properties of individual WS2 nanotubes will be discussed in some detail. The agreement between theory and experiment suggests that the nanotubes are of high crystalline order and their mechanical properties are predictable.The study of MoS2 nanooctahedra 2-5 nm in size, which can be considered to be the true inorganic fullerenes of these and many other layered structures, will be discussed. The agreement between the calculated and experimentally observed structures indicate that the nanooctahedra are indeed the stable structures in this size range, beyond this size the quasi-spherical nested MoS2 structures become stable.Some new potential applications for these and related materials will be discussed in the fields of friction reduction of various objects; catalysis; rechargeable batteries, coatings, etc. will be discussed as well.
9:30 AM - Q11.2
Molecular Beam Epitaxy Growth of CdTe over Carbon Nanotubes.
Rodolfo Camacho 1 , Stephan Turano 1 , W. Jud Ready 1
1 GTRI-EOSL, Georgia Tech, Atlanta, Georgia, United States
Show Abstract9:45 AM - Q11.3
SiC Nanowires by Silicon Carburization.
Loucas Tsakalakos 1 , Jody Fronheiser 1 , Larry Rowland 1 , Mohamed Rahmane 1 , Michael Larsen 1 , Yan Gao 1
1 , General Electric - Global Research Center, Niskayuna, New York, United States
Show AbstractNanowires and related one-dimensional nanostructures have recently been shown to be important building blocks for nanosystems with significantly improved or completely new performance capabilities compared to micro-devices. SiC nanowires have been the subject of particular interest due to their wide-bandgap (Eg = 2.2 eV), high electron mobility (1000 cm2/V-s), high breakdown field, and high temperature stability, making them promising candidates for nanoscale UV LEDs, harsh environment sensors, and electronics. While most SiC nanowires materials studied are nominally single crystals, polycrystalline SiC nanowires may also be of interest as toughening elements in mechanical load bearing nanocomposites or as field emitters. Numerous methods for synthesizing SiC nanowires have been described in the literature. These include metalorganic chemical vapor deposition (MOCVD), microwave plasma CVD, direct heating of substrates, nanotube confined reactions, thermal evaporation of powders, hot filament CVD, and sputtering combined with rapid thermal annealing. Recently we proposed and demonstrated a method to synthesize transition metal carbide nanowires using a two-step process in which metal or metal oxide nanowires are first formed on a Si substrate and subsequently carburized in situ by flowing methane and hydrogen [L. Tsakalakos, et al., J. Appl. Phys. 98, 044317 (2005)]. Mo2C nanowires and nanoribbons were grown on Si and the growth mechanism was shown to be due to a complex interaction of MoxOy vapor species with Au catalyst on the Si surface, leading to an autocatalytic growth. Here we describe a similar, yet mechanistically less complicated, method for making SiC nanowires in which Si nanowires are grown using the VLS mechanism, followed by carburization in methane or propane. This method allows us to synthesize nanowires that are fully polycrystalline 3C SiC or composites of Si nanowires covered with nano-sized SiC grains. Si nanowires are grown at low temperature (550-650 C) and subsequently carburized at 1100-1200 C in a methane/hydrogen or propane/hydrogen environment. Thermochemical calculations showed that the Si carburization is thermodynamically favorable over a wide tempareture range, whereas our studies showed that the Si nanowire carburization is kinetically limited below 1100 °C. Partially carburized nanowires contained distinct SiC nanosized grains on the Si nanowire surface, whereas fully carburized nanowires were polycrystalline 3C SiC with grain sizes of ~ 50-100 nm.
10:00 AM - **Q11.4
Inorganic Nanowires: Growth and Applications in Electronics and Optoelectronics.
Meyya Meyyappan 1
1 Center for Nanotechnology, NASA Ames Research Center, Moffett Field, California, United States
Show Abstract10:30 AM - Q11.5
Fabrication of Spinel Nanotubes Based on Kirkendall Effect.
Hongjin Fan 1 , Mato Knez 1 , Roland Scholz 1 , Kornelius Nielsch 1 , Eckhard Pippel 1 , Dietrich Hesse 1 , Margit Zacharias 1 2 , Ulrich Goesele 1
1 Dep. II, MPI of Microstructure Physics, Halle Germany, 2 FWIM, FZ Rossendorf, Dresden Germany
Show Abstract10:45 AM - Q11.6
Self-organized TiO2 Nanotubes and Their Applications.
Jan Macak 1 , Hiroaki Tsuchiya 1 , Andrei Ghicov 1 , Eugeniu Balaur 1 , Patrik Schmuki 1
1 Dep. of Materials Science, Chair for Surface Science, Erlangen, Bavaria, Germany
Show AbstractThe presentation deals with self-organized high aspect ratio titania nanotubes that can be produced by tailored electrochemical anodization. Tubes can be grown to the length of several micrometers with single tube diameter of several tens of nm and with the possibility to modify the geometry (1-4). This strategy to form self-organized structures can be used also for the whole range of other valve metals such as Hf (5), Zr (6), Nb (7), Ta (8) or Titanium alloys (9,10). We show that self-organized highly ordered nanotubes are formed under a competition of TiO2 formation and its dissolution. Using various growth conditions the pore geometry can be varied significantly. Particularly TiO2 nanotubes have found considerable interest due to a wide range of different functional properties. The tubes can be dye-sensitized or (11) or N-doped (12, 13) and be used for solar energy conversion, or for the catalytical electrooxidation of methanol (14). Further, interactions with hydroxyapatite (15) and changing of wettability (16) have been investigated for biomedical purposes. These issues will be discussed in detail.References:1. V. Zwilling, E. Darque-Ceretti, A. Boutry-Forveille, D. David, M.Y. Perrin, M. Aucouturier, Surf. Interface Anal. 27, 629 (1999).2. J. M. Macak, K. Sirotna and P. Schmuki, Electrochim. Acta, 50, 3679 (2005).3. J. M. Macak, H. Tsuchiya and P. Schmuki, Angew. Chem., 44, 2100 (2005).4. J. M. Macak, H. Tsuchiya, L.V. Taveira, S. Aldabergerova, P. Schmuki, Angew. Chem. 44, 7463 (2005)5. H. Tsuchiya and P. Schmuki, Electrochem. Commun., 7, 49 (2005).6. H. Tsuchiya and P. Schmuki, Electrochem. Commun., 6, 1131 (2004).7. I. Sieber, H. Hildebrand, A. Friedrich and P. Schmuki, Electrochem. Commun., 7, 97 (2005).8. I. Sieber, B.Kannan, P. Schmuki, Electrochem. Solid-State Lett., 8, J10 (2005).9. J. M. Macak, H. Tsuchiya, L.V. Taveira, A. Ghicov, P.Schmuki, J. Biomed. Mater. Res. 75A, 928 (2005).10. H. Tsuchiya, J.M. Macak, A.Ghicov, P. Schmuki, Small 2, 888 (2006).11. J.M. Macak, H. Tsuchiya, A. Ghicov, P.Schmuki, Electrochem. Comm. 7, 1133 (2005).12. R.P. Vitiello, J. M. Macak, A. Ghicov, H. Tsuchiya, L.F.P. Dick, P. Schmuki, Electrochem. Commun. 8, 544 (2006).13. A. Ghicov, J. M. Macak, H. Tsuchiya, J. Kunze, V. Haeublein, L. Frey, P. Schmuki, NanoLetters 6, 1080 (2006).14. J. M. Macak et al., Electrochem. Commun. 7, 1417 (2005).15. H. Tsuchiya et al., J. Biomed. Mater. Res. 77A, 534 (2006).16. E. Balaur, J. M. Macak, H. Tsuchiya, P. Schmuki, J. Mater. Chem 15, 4488 (2005).
Q12: Si/Ge Based Nanowires
Session Chairs
Prabhakar Bandaru
Reshef Tenne
Wednesday PM, November 29, 2006
Room 312 (Hynes)
11:30 AM - **Q12.1
Carbon Nanotubes, Innovations to Applications.
Wonbong Choi 1
1 Department of Engineering and Computing, Florida International University, Miami, Florida, United States
Show Abstract12:00 PM - Q12.2
Synthesis of Heteroepitaxially Aligned Ge Nanowires and Ge/Si Core/Shell Nanowires.
Irene Goldthorpe 1 , Paul McIntyre 1
1 Materials Science and Engineering, Stanford University, Stanford, California, United States
Show AbstractGe nanowires (NWs) have been less extensively studied than Si NWs, however, they offer advantages such as a lower synthesis temperature and higher intrinsic electronic carrier mobilities. In this work, Ge NWs with diameters of 50 nm and less have been heteroepitaxially grown on Si (111) substrates in a cold-wall CVD reactor. To obtain arrays of wires with similar lengths and diameters, monodisperse Au nanoparticles were used as the catalysts. Because these nanoparticles are generally suspended in an aqueous solution, this presents challenges for obtaining epitaxial NW growth on Si. We will describe how sample preparations dictate the quality of the epitaxial relationship between the wires and the substrate. The epitaxial relationship between the GeNWs and the Si substrate was quantitatively studied by x-ray diffraction, including detailed symmetric and asymmetric diffraction scans, and x-ray pole figures. The pole figures indicated that the majority of wires are heteroepitaxial, however, there exists a low density of twinning defects at the Ge/Si interface at the bases of both vertically oriented wires and wires oriented along inclined <111> directions. X-ray diffraction was also used to characterize the strain state of the Ge NWs. Even though the wires have a thin native oxide layer, no axial component of strain in the Ge NWs was measured by symmetric x-ray diffraction from vertical NW arrays. Heteroepitaxially depositing a Si shell around the Ge NWs may allow for the engineering of strain inside the NWs and reduce the influence of surface defects in carrier scattering by confining carriers to the NW interior. We will compare different strategies of Ge/Si core/shell NW synthesis and report the conditions which dictate whether three-dimensional Si islands or a continuous amorphous, polycrystalline, or crystalline Si film forms around the Ge cores.
12:15 PM - Q12.3
Feasibility of Si Nanowire Integration: CVD Growth, Characterization and Comparison of Au vs PtSi Catalysts.
Baron Thierry 1 , Michael Gordon 1 , Florian Dhalluin 1 , Martien Den Hertog 3 , Pierre Ferret 2 , Pascal Gentile 3 , Celine Ternon 1 , Karim Aissou 1 , Jean-Luc Rouviere 3
1 LTM, CNRS, Grenoble France, 3 , CEA/DRFMC, Grenoble France, 2 , CEA/DRT, Grenoble France
Show Abstract12:30 PM - Q12.4
Theoretical and Experimental Studies of Au-Ge Liquidus Behavior in Germanium Nanowire Nucleation and Growth.
Hemant Adhikari 1 , Ann Marshall 2 , Christopher Chidsey 3 , Paul McIntyre 1
1 Materials Science and Engineering, Stanford University, Stanford, California, United States, 2 Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California, United States, 3 Chemistry, Stanford University, Stanford, California, United States
Show Abstract12:45 PM - Q12.5
Silicon Nanowire Synthesis on Metal Implanted Silicon Substrates.
Thomas Stelzner 1 2 , Gudrun Andrae 2 , Elke Wendler 1 , Werner Wesch 1 , Danilo Zschech 3 , Martin Steinhart 3 , Alexey Milenin 3 , Ulrich Goesele 3 , Silke Christiansen 3 4
1 Institute of Solid State Physics, Friedrich Schiller University, Jena Germany, 2 Laser Technology, Institute of Physical High Technology, Jena Germany, 3 , Max Planck Institute of Microstructure Physics, Halle Germany, 4 Physics, Martin Luther University Halle-Wittenberg, Halle Germany
Show AbstractVarious methods have been developed to synthesize one-dimensional nanostructures including vapor-liquid-solid (VLS) growth. VLS growth using chemical vapor deposition (CVD) is based on the cracking of a gaseous precursor, such as silane (SiH4), and the supersaturation of nano-sized liquid droplets of a catalyst metal, such as gold, forming a low temperature eutectic with silicon. The gold-silicon alloy droplet becomes supersaturated with silicon and nanowire growth starts to occur at the solid-liquid interface.We introduced gold catalyst by ion implantation, a few 10 nm below the silicon wafer surface and studied how gold droplets of a few 10 nm in diameter reach the substrate surface upon annealing and how these droplets yield the growth of silicon nanowires (SiNWs) by CVD. Gold implantation with high ion fluences leads to the amorphization of a surface near layer (~30nm) of the silicon wafer. In this amorphized silicon the gold diffusion is eased by diffusion coefficients four orders of magnitude higher than in crystalline silicon. After annealing at 350°C for 1 hour, amorphous or nanocrystalline gold nanoparticles of a few nanometers in diameter form throughout the entire amorphous silicon (a-Si) layer. At higher annealing temperatures (>600°C, 1 hour) the gold particles crystallize, grow and reside essentially at the wafer surface. In addition, the a-Si re-crystallizes, essentially epitaxially to the underlying wafer. The gold particles at the wafer surface can initialize VLS growth of nanowires in a CVD process. The approach to deposit the catalyst for VLS growth by using ion implantation has the potential to implant through wafer level stencil masks thereby obtaining regular catalyst nanopatterns on wafer-level. First results will be presented using a diblock-copolymer mask for patterning. Moreover, spatially resolved ion implantation and nanowire growth can be obtained by using a focused ion beam to insert the metal catalyst. Furthermore, the new implantation based templating method is less prone to oxide formation that alters the epitaxial growth of silicon nanowires, since the metal droplets reach the surface only upon annealing, i.e. during the CVD process if desired. This might be especially important when using metals other than gold with a better compatibility to semiconductor technology such as Ga, In, or Al, which oxidize easily.
Q13: Electrical Characterization of CNTs
Session Chairs
Wednesday PM, November 29, 2006
Room 312 (Hynes)
2:30 PM - **Q13.1
Nanogenerators – Working Principle and Potential Applications.
Zhong Wang 1
1 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractDeveloping novel technologies for wireless nanodevices and nanosystems are of critical importance for in-situ, real-time and implantable biosensing, biomedical monitoring and biodetection. An implanted wireless biosensor requires a power source, which may be provided directly or indirectly by charging of a battery. It is highly desired for wireless devices and even required for implanted biomedical devices to be self-powered without using battery. Therefore, it is essential to explore innovative nanotechnologies for converting mechanical energy (such as body movement, muscle stretching), vibration energy (such as acoustic/ultrasonic wave), and hydraulic energy (such as body fluid and blood flow) into electric energy that will be used to power nanodevices without using battery. It also has a huge impact to miniaturizing the size of the integrated nanosystems by reducing the size of the power generator and improving its efficiency and power density. We have demonstrated an innovative approach for converting nano-scale mechanical energy into electric energy by piezoelectric zinc oxide nanowire (NW) arrays [1, 2]. By deflecting the aligned NWs using a conductive atomic force microscopy (AFM) tip in contact mode, the energy that was first created by the deflection force and later converted into electricity by piezoelectric effect has been measured for demonstrating nano-scale power generator. The operation mechanism of the electric generator relies on the unique coupling of piezoelectric and semiconducting dual properties of ZnO as well as the elegant rectifying function of the Schottky barrier formed between the metal tip and the NW. The efficiency of the NW based piezo-electric power generator is ~ 17-30%. [1] Zhong Lin Wang and Jinhui Song, Science, 312 (2006) 242-246.[2] X.D. Wang, J.H. Song, C.J. Summers, J.H. Ryou, P. Li, R.D. Dupuis, and Z.L. Wang, J. Phys. Chem. B, 110 (2006) 7720-7724.[3] http://www.nanoscience.gatech.edu/zlwang/
3:00 PM - Q13.2
Dynamic Response of Carbon Nnanotube Field-effect Transistors in the GHz Range Analysed by S-parameters Measurements.
Jean-Marc Bethoux 2 , Henri Happy 2 , Gilles Dambrine 2 , Vincent Derycke 1 , Marcelo Goffman 1 , Jean-Philippe Bourgoin 1
2 , IEMN, Villeneuve d'Ascq France, 1 SPEC, CEA Saclay, Gif sur Yvette France
Show Abstract3:15 PM - Q13.3
Radio Frequency Conductivity Measurements of Silicon Nanowire Networks.
Wenchong Hu 1 , Alexey Kovalev 1 , Sarah Dilts 2 , Yanfeng Wang 1 , Bangzhi Liu 2 , Suzanne Mohney 1 , Joan Redwing 1 , Theresa Mayer 1
1 Department of Electrical Engineering, The Pennsylvania State University, University Park, State College, Pennsylvania, United States, 2 Department of Materials Science and Engineering, The Pennsylvania State University, State College, Pennsylvania, United States
Show Abstract3:30 PM - Q13.4
Frequency-Dependent Capacitance of Carbon Nanotube Thin Film Transistors Fabricated on SiO2 for Chemical Sensing Applications.
Gokhan Esen 1 2 , Michael Fuhrer 1 2 , Jian Chen 1 3 , Masa Ishigami 1 3 , Ellen Williams 1 3
1 Physics, University of Maryland at College Park, College Park, Maryland, United States, 2 Center for Superconductivity Research, University of Maryland at College Park, College Park, Maryland, United States, 3 Laboratory for Physical Sciences, University of Maryland at College Park, College Park, Maryland, United States
Show Abstract3:45 PM - Q13.5
Effects of Current-Induced Annealing on Charge and Spin Transport in Carbon Nanotube Devices.
Chen-Wei Liang 1 , Serhat Sahakalkan 1 , Siegmar Roth 1
1 , Max-Planck-Institute, Stuttgart Germany
Show AbstractCurrent-induced annealing has strong influence on charge and spin transport in single wall carbon nanotube field effect transistor (SWNTFET). After applying high current through carbon nanotube devices, both contact resistance and threshold voltage decreased dramatically. A progress of Coulomb-Blockade-to-Fabry-Pérot transition can be observed when annealing samples several times. On the other hand, the peaks of Column-Blockade, which were originally asymmetrical to the zero gate voltage, became symmetrical. This indicates that the annealing does not only reduce the contact resistance but also clean the body of carbon nanotube. To study how the annealing affects the spin transport, we measured the magnetoresistance of SWNTFET with Co contacts before and after annealing. Results show that the magnetoresistance either became larger or inversed from positive to negative.
Q14: Field Emission and Electrical Devices
Session Chairs
Wednesday PM, November 29, 2006
Room 312 (Hynes)
4:30 PM - **Q14.1
Cold Cathode Applications of Carbon Nanotubes.
William Milne 1
1 Electrical Engineering Department, University of Cambridge, Cambridge United Kingdom
Show AbstractMicro and nano-structurally rich carbon materials are alternatives to conventional metal/silicon tips for cold cathode (field emission) sources. In particular, carbon nanotubes exhibit extraordinary field emission properties because of their remarkable electrical conductivity, their high aspect ratio "whisker-like'' shape for optimum geometrical field enhancement, and excellent thermal stability. In this talk I will describe the growth of CNTs and their application in a range of cold cathode field emission based systems including their use in SEM sources, emitters for use in microwave amplifiers and in Field Emission Based displays (1).1 “Carbon nanotubes as field emission sources” W.I.Milne, K.B.K. Teo, G.A.J. Amaratunga, P.Legagneux, L,Gangloff, J.P. Schnell, V.Semet, V.T Binh and O Grtoening, Journal of Materials Chemistry 14 (6): 933-943 2004
5:00 PM - Q14.2
In search of Potential Cold Cathodes: Are Carbon Nanotubes the Candidate?
Sanju Gupta 1
1 Physics and Materials Science, Missouri State University, Springfield, Missouri, United States
Show AbstractMaterials science is playing a dramatic role in discovering new materials with tailored physical properties. Cold cathodes/field emitters are one of the examples. Electron field emitting materials are of vital importance for a variety of vacuum microelectronic devices including field emission displays for flat panel displays, electron microscopes, X-ray generators, and vacuum lamps. This is the driving force to investigate the advanced nanostructured carbons as cold cathodes as one of the potential candidates. Recently, they are also being proposed for thermionic power generators. The rationale is that reducing one or more dimensions of a system below some critical length changes the systems’ physical properties, where carbon nanotubes (CNTs) in the class of carbon nanostructures serve as a model example [1, 2]. We will present the synthesis and characterization of vertically aligned multiwall and single-/double-wall carbon nanotube films using a microwave plasma-assisted chemical vapor deposition technique. Recent advances in their synthesis, processing, and characterization indicate that the above mentioned potential is slowly being realized. Experiments showed that by continuous reduction in the thickness of the catalyst film produces hollow concentric tubes in contrast to bamboo-like multiwalled tubes with larger thickness. In relation to synthesis, the proposed growth model in terms of thermodynamic parameter will be discussed. To assess the electron field emission properties, besides the traditional field emission (I-V) properties, temperature dependent field electron emission microscopy (T-FEEM) enabling real-time imaging of electron emission providing information on emission site density, temporal variation of the emission intensity, and insight into the role of adsorbates from nanotube films will be discussed. Physics based models (such as negative or low electron affinity, geometric enhancement, surface dipole, tunneling due to adsorbates, structure modification due to doping etc.) will be described to support the experimental observations in addition to weak thermionic contribution. These findings indeed provided a great insight into the field emission mechanism and a contrasting comparison between small and large diameter carbon nanotubes. [1] Gupta et. al. Appl. Phys. Lett. 86, 063109 (2005). [Virtual Journal of Nanoscale Science and Technology, October 11 Issue, 2004]; [2] Gupta, et. al. J. Appl. Phys. 95, 8314 (2005). [Virtual Journal of Nanoscale Science and Technology, July 14 Issue, 2004].
5:15 PM - Q14.3
Quantum Transport and Trap Effects in Tunneling Rate Measurements of Metal Nanocrystal Based Carbon Nanotube Memory.
Udayan Ganguly 1 2 , Tuo-Hung Hou 3 , Edwin Kan 3
1 Nanotechnology, NASA Ames Research, Moffet Field, California, United States, 2 Dept. of Materials Science and Engineering , Cornell University, Ithaca, New York, United States, 3 School of Electrical and Computer Engineering, Cornell University, Ithaca, New York, United States
Show Abstract5:30 PM - Q14.4
A Compact Single-Walled Carbon Nanotube Transistor Integrated with Silicon MOSFET Using a Single Common Gate.
Hao Lin 1 , Yong Park 2 , Sandip Tiwari 3
1 Applied and Engineering Physics, Cornell University, Ithaca, New York, United States, 2 , Namseoul University, Chonan-si Korea (the Republic of), 3 Electrical and Computer Engineering, Cornell University, Ithaca, New York, United States
Show AbstractCarbon nanotubes potentially provide high current drive and high transconductance in transistors because of superior electron and hole transport, and are also potentially useful as sensors. However, integration of carbon nanotube, control of placement, good contacts, and suppression of instabilities and drift continue to be a problem. Compactness of structures is essential in most electronic and sensing applications. In this work, we have implemented a compact integrated structure with a silicon MOSFET on the bottom and a carbon nanotube MOSFET on the top, both sharing a common gate. Such a structure is an inverter and a prototype for a sensor where the nanotube is exposed to the ambient. Its uniqueness is in sharing the gate – a buried gate. Difficulties in making local back gate device comes from the need for planarization of the back gate to the surrounding insulating material – usually silicon dioxide. In our novel approach of fabricating single-walled carbon nanotube local back gate, devices with good planarization and thin gate dielectric film are achieved. Damacene process was employed to obtain the planarized gate structure. Both polysilicon and tungsten are employed as gates using chemical mechanical polishing. The control oxide for the nanotube is either a grown oxide from polysilicon or a deposited oxide for tungsten. A variety of structures, with oxide thickness of 8-10 nm have been fabricated using an approach that is compatible with silicon technology and allows integration of carbon nanotube devices on top of CMOS circuits. In addition to the devices and their chracteristics, we also demonstrate an inverter with a p-type CNTFET placed directly on top of an n-type MOSFET, both of which are controlled by the same polysilicon gate in between. The approach provides high density and potentially provides high local gain for ultra-sensitive detection using CMOS circuits underneath.
5:45 PM - Q14.5
Synthesis of Metal-Oxide-Metal (MOM) Heterojunction Nanowires for Chemical Sensing, Ferroelectric, and Piezoelectric Functions.
Edward Herderick 1 , Jason Tresback 1 , Alexander Vasiliev 1 , Nitin Padture 1
1 Materials Science and Engineering, The Ohio State University, Columbus, Ohio, United States
Show Abstract There is growing interest in the field of nanoelectronic devices, where nanoscale building blocks, such as nanowires (metals, semiconductors, oxides), are fabricated in isolation and assembled into nanocircuits. In the case of functional oxides, currently all-oxide nanowires are assembled across metal contact-pad electrodes to create devices, where the oxide active region is determined by the distance the spanning the electrodes. In this context, metal-oxide-metal (MOM) heterojunction nanowires, where two Au nanowires (50-100 nm diameter and several microns in length) are separated by a nanoscale segment (50-100 nm diameter and length) of a functional oxide, offer several advantages over all-oxide nanowires. Here the metal interconnects are integrated within the building block making them more suitable for large-scale assembly, as well as providing Schottky junctions and cataylsis sites for sensing applications. In addition, the small interfacial area of the metal interconnects and the oxide offer the possibility of measuring coupled electronic properties of these nanoscale oxides without substrate effects. We have developed a novel, template-based method for the synthesis of Au-ZnO-Au, Au-TiO2-Au, and Au-BaxSr(1-x)TiO3-Au nanowires. Results from the synthesis and characterization of these MOM nanowire structures will be presented, as well as a discussion of relevant properties and device applications.
Q15: Poster Session: Nanotubes and Nanowires: Electrical Properties & Devices
Session Chairs
Prabhakar Bandaru
Morinobu Endo
Ian Kinloch
Apparao Rao
Thursday AM, November 30, 2006
Exhibition Hall D (Hynes)
9:00 PM - Q15.1
Length Characterization of Single Walled Carbon Nanotubes using Resonance Raman Spectroscopy.
Shin Chou 1 , H. Son 2 , M. Zheng 3 , Ado Jorio 4 , R. Saito 5 , Gene Dresselhaus 6 , Mildred Dresselhaus 2 7
1 Chemistry, MIT, Cambridge, Massachusetts, United States, 2 EECS, MIT, Cambridge, Massachusetts, United States, 3 DuPont Central Research and Development, Experimental Station, , Wilmington, Delaware, United States, 4 Physics, Universidade Federal de Minas Gerais, Belo Horizonte Brazil, 5 Physics, Tohoku University, Sendai Japan, 6 Francis Bitter Magnet Laboratory, MIT, Cambridge, Massachusetts, United States, 7 Physics, MIT, Cambridge, Massachusetts, United States
Show Abstract9:00 PM - Q15.10
Wide Bandgap Semiconductors - Nanowires of p- and n-type Silicon Carbide
Bettina Friedel 1 , Siegmund Greulich-Weber 1
1 Department of Physics, University of Paderborn, Paderborn Germany
Show AbstractMonocrystalline nanowires of cubic silicon carbide were synthesized using a combined sol-gel and carbothermal reduction process in which tetraethoxysilane was used as primary silicon and sucrose as carbon source. The diameters of the as-grown nanowires varied depending on process parameters from several tens to several hundreds nanometers, whereas the length of the wires was located in the millimetre region. By precisely controlling the atomic ratio of Si / C, silicon carbide nanowires were synthesized exclusively and pure without the presence of residual carbon or unwanted silica, thus leads to semi-insulating behaviour. Supported by their consistence the silicon carbide nanowires can be processed to textile or felt structures and are therefore usable for many applications such as for fireproof clothing, high temperature or chemical filters and composite materials. Additionally during sol-gel synthesis the silicon carbide nanowires were easily doped to achieve p- or n-conduction, guiding to new applications in the field of wide bandgap semiconductors. The structure of 3C-SiC nanowires was determined using scanning electron microscopy, X-ray diffraction, nuclear magnetic resonance and fourier transform infrared spectroscopy. The electronic properties were studied using electron paramagnetic resonance spectroscopy and current-voltage measurements.
9:00 PM - Q15.11
Electric Field Dependence of the Raman Spectra in Single-wall Carbon Nanotube Thin Film Networks.
Giovanni Fanchini 1 , Husnu Unalan 1 , Manish Chhowalla 1
1 , Rutgers University, Piscataway, New Jersey, United States
Show Abstract9:00 PM - Q15.12
Measurement of Minority Carrier Diffusion Lengths in Semiconductor Nanowires.
Jonathan Allen 1 , Yi Gu 1 , Eric Hemesath 1 , Lincoln Lauhon 1
1 Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States
Show AbstractSemiconductor nanowires have been identified as potential candidates to replace traditional CMOS technology, but quantitative measurements of device figures of merit are not abundant. This is due in part to the challenge of identifying and/or adapting characterization techniques that are suitable for very small devices. The realization of reliable nanowire device technology can therefore be facilitated by the development of techniques to quantify fundamental metrics including carrier mobility, diffusion, and lifetime. Here we report the first quantitative measurement of minority carrier diffusion lengths in semiconductor nanowires using an electron beam induced current (EBIC) technique. Two-terminal Schottky diode devices were fabricated using n-type Si nanowires grown via the vapor-liquid-solid growth mechanism. Ohmic contacts were made using Ni while Au was used for Schottky contacts. Scanning the devices with an electron beam provided a highly localized source of excess carriers whose effects were monitored as changes in device current. In Schottky diode devices under reverse bias, this response was localized near the Schottky contact and decayed exponentially along the device channel with characteristic decay constant, L, the minority carrier diffusion length. In heavily doped (Si:P ~ 500:1) n-type silicon nanowires of diameter 20 nm, L was found to be ~30 nm, and was insensitive to changes in source-drain bias and electron beam power. L was also measured as a function of nanowire diameter and doping concentration in order to investigate the role of surface effects and carrier-carrier interactions. Analysis of the generation region suggests that secondary electrons play a negligible role in the measured response. The measurement resolution is sufficient to provide a reliable measurement of the 30 nm diffusion lengths reported here and is significantly higher than our previously reported resolution using scanning photocurrent microscopy[Y. Gu et al, Nano Letters 6, 948 (2006)]. Minority carrier diffusion length is a key parameter in determining semiconductor device performance. The measurements described above can therefore contribute to the development and optimization high-performance devices based on semiconductor nanowires.
9:00 PM - Q15.13
Absorption Cross Section and Quantum Efficiency of Pristine and Boron-doped Single-walled Carbon Nanotubes.
Jeffrey Blackburn 1 , Timothy McDonald 1 2 , Thomas Gennett 1 3 , Yanfa Yan 1 , Kim Jones 1 , Chaiwat Engtrakul 1 , Kelly Knutson 1 , Randy Ellingson 1 , Garry Rumbles 1 , Michael Heben 1
1 Basic Science, National Renewable Energy Lab, Golden, Colorado, United States, 2 Applied Physics, Columbia University, New York, New York, United States, 3 Chemistry, Rochester Institute of Technology, Rochester, New York, United States
Show Abstract9:00 PM - Q15.14
aF Resolution C-V Characterization of Nano-scale FETs Using Ambient Noise and Non-linearities.
Ali Gokirmak 1 , Hazer Inaltekin 1
1 Electrical and Computer Engineering , Cornell University, Ithaca, New York, United States
Show Abstract9:00 PM - Q15.15
Ternary PtRuNi Nanocatalysts Dispersed on Multiwall Carbon Nanotubes for Methanol Electro-oxidation in Acid Medium.
Yu-Kuei Hsu 1 , Wei-Horng Su 1 2 , Yan-Gu Lin 3 4 , Ju-Lan Yang 3 , Chia-Liang Sun 1 , San-Yuan Chen 3 , Chii-Ruey Lin 2 , Kuei-Hsien Chen 1 4 , Li-Chyong Lin 4
1 , Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei Taiwan, 2 , Institite of Mechatronic Engineering, National Taipei University of Technology, Taipei Taiwan, 3 , Los Alamos National Lab, Hsinchu Taiwan, 4 , Center for Condensed Matter Sciences, National Taiwan University, Taipei Taiwan
Show Abstract9:00 PM - Q15.16
FET Properties of Surface Silylated Single Wall Carbon Nanotubes.
Ryotaro Kumashiro 1 7 , Nobuya Hiroshiba 1 , Hirotaka Ohashi 1 , Takeshi Akasaka 2 , Yutaka Maeda 3 , Shinzo Suzuki 4 , Yohji Achiba 5 , Rikizo Hatakeyama 6 , Katsumi Tanigaki 1 7
1 Department of Physics, Graduate School of Science, Tohoku University, Sendai Japan, 7 CREST, Japan Science and Technology Agency, Kawaguchi Japan, 2 Center for Tsukuba, Advanced Research Alliance, University of Tsukuba, Tsukuba Japan, 3 Department of Chemistry, Tokyo Gakugei University, Tokyo Japan, 4 Faculty of Science, Kyoto Sangyo University, Kyoto Japan, 5 Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo Japan, 6 Graduate School of Engineering, Tohoku University, Sendai Japan
Show AbstractSingle wall carbon nanotubes (SWNTs) having semiconducting properties are promising as electronic materials for nano-scale devices in the future, and the electrical properties of SWNTs are of significantly fundamental and practical interests. It is well known that the field effect transistors (FETs) fabricated using semiconducting SWNTs show high performance in terms of the mobility. However, carriers in pristine SWNTs are mostly holes and, therefore, SWNTs -FETs usually show p-type properties. As for SWNTs, chemical carrier doping has been reported so far for controlling carrier concentration like graphite intercalations. Two major techniques in SWNTs are generally possible; one is endohedral doping and the other is the exohedral chemical modifications. It has been exemplified that doping with alkali metals can introduce electron carriers into SWNTs. Furthermore, the electrical transport properties of SWNTs were reported to be controlled by the endohedral insertion of organic molecules inside the SWNTs. A similar carrier doping could exohedrally be possible when the SWNTs surface is chemically modified. With such chemical modifications, the charge transfer from the substituent groups to SWNTs will be expected and this could modify the electronic states of SWNTs.We reported the FET properties of individual SWNTs exohedrally modified by Si-containing organic moieties, and demonstrated that p-type nanotubes can be converted to n-type ones. However, because of ununiformity of the surface-chemical modifications of SWNTs, the true effects of the exohedral modifications on FET properties were extremely difficult to be evaluated. In this meeting, we will present comparison of the FET properties of the exohedrally silylated SWNTs between separated individual and spread-sheet samples. For evaluating the FET properties, the chemically modified SWNTs have been dispersed on a FET substrate, and the measurements have been carried out at ambient temperature using a conventional method for a separated SWNTs and a spread-sheet SWNTs film. As a reference, the experiments were also made in the same manner on chemically non-modified CNTs. From the experimental results, it will be demonstrated that an n-type property can be enhanced by the exohedral modifications both in the case of the spread-sheet samples and in the case of the individual ones. We will discuss the effects of surface silylation on the electronic states of these SWNTs.
9:00 PM - Q15.17
Performance of Thin Film Transistors from Brominated Single Wall Carbon Nanotube Networks.
Giovanni Fanchini 1 , Husnu Unalan 1 , Manish Chhowalla 1
1 , Rutgers University, Piscataway, New Jersey, United States
Show Abstract9:00 PM - Q15.18
Ba6Mn24O48 Whiskers: A New Material for Batteries, Sensors and Catalysis.
Ekaterina Pomerantseva 1 , Eugene Goodilin 1 , Marina Kozlova 1 , Valery Krivetsky 2 , Lyudmila Leonova 2 , Yuri Dobrovolsky 2 , Yuri Tretyakov 1
1 Department of Materials Science, Lomonosov Moscow State University, Moscow Russian Federation, 2 , Institute of Problems of Chemical Physics, Chernogolovka Russian Federation
Show Abstract9:00 PM - Q15.19
Rare Earth Implanted Nanowires.
Sebastian Geburt 1 , Daniel Stichtenoth 1 , Sven Müller 1 , Wilma Dewald 1 , Quan Li 2 , Carsten Ronning 1
1 II. Institute of Physics, University of Göttingen, Göttingen Germany, 2 Department of Physics, Chinese University of Hong Kong, Shatin Hong Kong
Show AbstractRare earth elements embedded in suitable matrices show optical active and sharp intra-4f-transitions with long life-times. E.g. such states are necessary for the realization of Nd:YAG-lasers. It is known that the geometry of semiconductor nanowires could act as cavity; therefore, rare earth doped semiconductor nanowires may be suitable for lasing issues. Silicon, ZnO and ZnS nanowires were grown according the VLS mechanism using the vapour transport technique. The resulting material was investigated by SEM, XRD, and TEM. After growth, the nanowires were brought into solution and dispersed onto clean silicon substrates. Rare earth elements were implanted into the nanowires with different ion fluences and ion energies. The ion energy, which determines the ion range, was set to match the diameter of the nanowires. The radiation defects were healed by annealing in vacuum. The structural changes of the nanowires upon implantation and annealing were investigated in detail by TEM as well as the optical properties using PL, time resolved PL and µ-PL. In this presentation, we will present the obtained results and discuss the feasibility of rare earth based nanowire-lasers.
9:00 PM - Q15.2
Raman Spectroscopy Studies on Pure Carbon Nanotube Fibres.
Anna Moisala 1 , Marcelo Motta 1 , Ian Kinloch 1 , Alan Windle 1
1 Dept. of Materials Science and Metallurgy, University of Cambridge, Cambridge, Cambs., United Kingdom
Show AbstractWe have previously introduced a catalytic gas-phase process for carbon nanotube (CNT) formation and collection in bulk quantities (Li et al. Science 304, 2004, 276-278). The major benefit of this process is the ability to collect the CNTs continuously as pure fibres or films. The method can be used to produce either multi- or single/double-walled nanotube fibres depending on the process conditions and reaction chemistry. Raman spectroscopy has been widely used for the characterisation of carbon nanotubes (e.g. Dresselhaus and Eklund Adv. Phys. 49, 2000, 705-814). This work discusses the use of Raman spectroscopy to study various aspects of the nanotube fibres. Polarised Raman measurements were carried out to study the nanotube and nanotube bundle alignment within the fibres. In situ Raman spectroscopy was used during mechanical testing of the fibres to study the deformation of the nanotubes upon stretching. The nanotube types were studied at various laser wavelengths (514, 633, 785 and 830 nm) and applying either holographic (notch) or near excitation tuneable (NExT) filters, which allowed the measurement down to approximately 10 cm-1 Raman shift. Characteristics of both single- and multiwalled nanotubes were observed in a single spectrum. These unique microstructures were also studied by scanning and transmission electron microscopy and X-ray diffraction.
9:00 PM - Q15.20
Morphology and Optical Properties of ZnO Nanorods Grown by Catalyst-assisted Vapor Transport on Various Substrates.
Vitaliy Avrutin 1 , U. Ozgur 1 , N. Izyumskaya 1 , S. Chevtchenko 1 , J. Leach 1 , J. Moore 2 , A. Baski 2 1 , H. Everitt 3 , K. Tsen 4 , M. Abouzaid 5 , P. Ruterana 5 , H. Morkoc 1 2
1 Department of Electrical and Compputer Engineering, Virginia Commonwealth University, Richmond, Virginia, United States, 2 Department of Physics, Virginia Commonwealth University, Richmond, Virginia, United States, 3 , Army Aviation & Missile RDEC, Redstone Arsenal, Alabama, United States, 4 Department of Physics and Astronomy, Arizona State University, Tempe, Arizona, United States, 5 SIFCOM, UMR 6176 CNRS-ENSICAEN, Caen France
Show Abstract9:00 PM - Q15.21
Experimentally Determined Absorption Cross-sections of Solution-based CdSe and CdTe Nanowires.
Vladimir Protasenko 1 , Daniel Bacinello 1 , Masaru Kuno 1
1 Chemistry, University of Notre Dame, South Bend, Indiana, United States
Show Abstract9:00 PM - Q15.22
Ultraviolet GaN Single Nanowire Light Emitting Diode.
Mariano Zimmler 1 , Jiming Bao 1 , Joonah Yoon 1 2 , George Seryogin 1 , Ilan Shalish 1 , Venkatesh Narayanamurti 1 , Federico Capasso 1
1 Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States, 2 Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractSemiconductor nanowires have been shown to exhibit many of the properties needed for future integrated nanoscale electronics and optoelectronics. [1] Central to their usefulness, however, is the ability to fabricate reliable electrical contacts for nanoscale light emitting diodes and lasers. Here we use a new and general strategy for efficient injection along the length of a semiconductor nanowire [2] to fabricate a GaN single nanowire light emitting diode, which may be used as a compact ultraviolet light source.GaN nanowires catalytically grown by hybrid vapor phase epitaxy [3] were placed between a heavily doped p-type silicon wafer and a metallic thin film, serving as hole—and electron—injecting contacts, respectively. A high-resolution negative electron beam resist is used as an insulating layer between the two contacts. [2]The single nanowire electroluminescence spectrum was measured as a function of temperature and applied voltage bias. The room temperature spectrum exhibits a distinct peak at 355 nm as well as a broad luminescence centered at ~720 nm. With decreasing temperature, both features are blue-shifted (340 nm and ~700 nm, respectively, at 5 K), and their relative magnitudes change, making the ultraviolet contribution sharply dominant.[1] Huang, Y.; Lieber, C. M. Pure Appl. Chem. 2004, 76, 2051.[2] Bao, J.; Zimmler, M. A.; Capasso, F.; Wang, X.; Ren, Z. F. To appear in Nano Lett.[3] Seryogin, G.; Shalish, I.; Moberlychan, W.; Narayanamurti, V. Nanotechnology 2005, 16, 2342.
9:00 PM - Q15.23
Active Semiconductor Nanowires for Functional Photonic Circuit Elements
Carl Barrelet 1 , Hong Gyu Park 1 , Yongning Wu 1 , Charles Lieber 1 2
1 Chemistry, Harvard University, Cambridge, Massachusetts, United States, 2 Division of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts, United States
Show Abstract9:00 PM - Q15.24
Raman Scattering Studies on Br2-doped Double Wall Carbon Nanotubes.
Antonio Souza 1 , Morinobu Endo 3 , H. Muramatsu 3 , T. Hayashi 4 , Y. Kim 3 , Eduardo Barros 1 , Riichiro Saito 5 , Ge Samsonidze 2 , Mildred Dresselhaus 2
1 Física, Universidade Federal do Ceara, Fortaleza, Ceara, Brazil, 3 Faculty of Engineering, Shinshu University,, Nagano Japan, 4 , Tokyo National College, Tokyo Japan, 5 Physics, Tohoku University, Sendai, Tohoku, Japan, 2 Electrical Engineering, MIT, Cambridge, Massachusetts, United States
Show Abstract9:00 PM - Q15.25
Optical Properties of 55Mn Implanted ZnS Nanowires.
Daniel Stichtenoth 1 , Sebastian Geburt 1 , Carsten Ronning 1 , Tobias Niebling 2 , Peter J. Klar 2
1 II. Institute of Physics, University of Göttingen, Göttingen Germany, 2 Physics and Material Sciences Center, Philipps-University of Marburg, Marburg Germany
Show Abstract9:00 PM - Q15.27
Investigation of the Epitaxial Growth of Zinc Oxide Nanowires on Sapphire by Grazing Incident Synchrotron X-ray Diffraction.
Rodrigo Lacerda 1 , Leonardo Campos 1 , Roberto Magalhães-Paniago 1 , Andre Ferlauto 1 , Sharvari Dalal 2 , Daniel Batista 2 , Sergio Oliveira 1 , W. Milne 2 , Luiz Ladeira 1
1 Departamento de Física, ICEX, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil, 2 Engineering Department, Cambridge University, Cambridge, CB2 1PZ, UK, United Kingdom
Show AbstractNew PresenterWednesday 11/29Poster Q15.27Investigation of the Epitaxial Growth of Zinc Oxide Nanowires on Sapphire by Grazing Incident Synchrotron X-ray Diffraction. Sharvari Dalal
9:00 PM - Q15.28
Investigation of the Optical Gap in Ge Nano-wires.
Scott Beckman 1 , Jiaxin Han 2 , James Chelikowsky 1 2 3
1 Center for Computational Materials, Institute for Computational Engineering Sciences, University of Texas at Austin, Austin, Texas, United States, 2 Department of Physics, University of Texas at Austin, Austin, Texas, United States, 3 Department of Chemical Engineering, University of Texas at Austin, Austin, Texas, United States
Show Abstract9:00 PM - Q15.29
Comparative Raman Spectroscopy Study of Single-Wall and Double-Wall Carbon Nanotube Systems Doped with H2SO4.
Eduardo Barros 1 , Antonio Souza Filho 1 , HyungBin Son 3 , Yoong-Ahm Kim 2 , Hiroyuki Muramatsu 2 , Takuya Hayashi 2 , Morinobu Endo 2 , Mildred Dresselhaus 3
1 Physics, Universidade Federal do Ceara, Fortaleza Brazil, 3 Electrical Engeneering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Electrical And Electronic Engineering, Shinshu University, Nagano Japan
Show Abstract9:00 PM - Q15.3
EDLC Properties Depend on the Diameter of Mass Produced Multi-walled Carbon Nanotubes.
Yong-Jung Kim 1 , Yusuke Abe 2 , Takashi Yanagiura 2 , Masaaki Kitani 2 , Tsuyoshi Kodama 2 , Keita Higuchi 2 , Morinobu Endo 1 2
1 , Institute of Carbon Science & Technology, Shinshu University, Nagano, Nagano, Japan, 2 Eletrical and electronics engineering, Shinshu University, Nagano, Nagano, Japan
Show AbstractTwo types of mass produced multi-walled carbon nanotubes (MWNTs, which is generally known as a VGCF) with different diameters (the trade mark of the thicker one is VGCF® and of the thinner one, VGNF®) have been investigated for their potential for use in electric double layer capacitors (EDLCs). The variation aspects of the two MWNTs by KOH activation depend on their diameters. The capacitance enhancement and specific surface area (SSA) on KOH activation is more drastic for the thicker MWNT (VGCF®). The VGCF-KOH 500 exhibits a capacitance enhancement as much as 30 times greater (37.2 F/g) than that of the as-grown materials (1.2 F/g), under the conditions of charging up to 3.5V and discharging at a current density of 10mA/cm2. Interestingly, only for the case of the thinner MWNT (VGNF®), selective attack on its amorphous carbon impurity has also been observed, but only the case of thinner MWNT (VGNF®) as demonstrated from both SEM observations and Raman spectra. Consequently, the results of this study will provide the insight into the potentiality of using MWNTs for EDLC electrodes, which would enable cheapest production cost among the various types of carbon nanotubes.
9:00 PM - Q15.30
Atomically Resolved Imaging on an Epitaxially Grown Silver Nanorod Surface.
Saw Hla 1 , Albert Prodan 2 , Herman van Midden 2
1 Physics & Astronomy, Ohio University, Athens, Ohio, United States, 2 Solid State Physics, J Stefan Institute, Ljubljana Slovenia
Show Abstract9:00 PM - Q15.31
Determination of Electron-Phonon Coupling in Carbon Nanotubes by Resonant Raman Scattering.
Yan Yin 1 , A. Vamivakas 2 , A. Walsh 1 , S. Cronin 3 , M. Unlu 2 1 , B. Goldberg 1 2 , A. Swan 2 1
1 Physics Department, Boston University, Boston, Massachusetts, United States, 2 Electrical and Computer Engineering Department, Boston University, Boston, Massachusetts, United States, 3 Electrical Engineering Department, University of Southern California, Los Angeles, California, United States
Show Abstract9:00 PM - Q15.32
Analysis of Carbon Nanomaterials Using Tip-Enhanced Near-Field Raman Spectroscopy.
Prabhat Verma 1 , Taka-aki Yano 1 , Yasushi Inouye 2 , Satoshi Kawata 1
1 Applied Physica, Osaka University, Suita, Osaka, Japan, 2 Dept. of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
Show AbstractThe spatial resolution in the optical microscopy of carbon nanostructures, such as carbon 60 (C-60) or carbon nanotube (CNT), is limited to the diffraction limits of the probing light, which is not small enough to characterize and image these nanostructures. The basic idea to overcome this diffraction-limited resolution in Raman scattering leaded to the discovery of tip-enhanced near-field Raman scattering (TERS). In this phenomenon, when light is incident on a nano-sized metallic tip, a nano-sized enhanced electric field is generated at the tip apex due to localized surface plasmon polariton excitation, which enhances Raman scattering from molecules existing only in the vicinity of the tip. Therefore, TERS can provide an enhancement with extremely high spatial resolution, far beyond the diffraction limits of the probing light. In the present study, TERS has been applied to analyze the nanoscale vibratioanal properties of C-60 molecules and single-wall CNT (SWCNT). A silver coated AFM cantilever tip with a tip-apex of 40 nm was approached to the C-60 molecules and individual SWCNT bundles, which were dispersed on glass coverslips, and the samples were illuminated by a green laser (wavelength: 532 nm). Compared to the far-field, huge enhancements in Raman scattering were observed in the near-field configuration. Further, super-resolved near-field Raman imaging of isolated SWCNT bundles was performed with a spatial resolution of 40nm by setting the spectrometer to a frequency corresponding to the radial breathing mode, and then raster-scanning the bundle under the silver-coated tip. In addition to the conventional topographic-type imaging, this nano-Raman image also showed a spatial distribution of the tube diameters within the bundles.
9:00 PM - Q15.33
Fabrication of Omega-shaped-gate ZnO Nanowire Field Effect Transistors.
Kihyun Keem 1 , Dong-Young Jeong 2 , Sangsig Kim 1 , Moon-Sook Lee 3 , In-Seok Yeo 3 , U-In Chung 3 , Joo-Tae Moon 3
1 Electrical Engineering, Korea University, Seoul Korea (the Republic of), 2 Institue for Nano Science, Korea University, Seoul Korea (the Republic of), 3 Memory Division R&D Center, Samsung Electronics Co., Yongin-City Korea (the Republic of)
Show Abstract9:00 PM - Q15.34
Electrical Properties of Metal Doped Vanadium Pentoxide Nanofibers.
Pil Soo Kang 1 , Hyeyeon Ryu 1 , Seongmin Yee 1 , Gyu-Tae Kim 1 , G. s. Zakharova 2 , V. l. Volkov 2
1 School of Electrical Engineering, Korea University, Seoul Korea (the Republic of), 2 Institute of Solid State Chemistry, Ural Division Russian Academy of Sciences, Yekaterinburg Russian Federation
Show Abstract9:00 PM - Q15.35
Electrical Property of Single Crystalline Dilute Magnetic GaMnN Nanowires.
Choi Sung-Churl 1 , Byeun Yun-Ki 1 2 , Lee Jin-Seok 1 , Han Kyoung-Sop 2
1 ceramic engineering, hanyang univeristy, Seoul Korea (the Republic of), 2 Material science, Korea Institute Science and Tehcnology, Seoul Korea (the Republic of)
Show Abstract9:00 PM - Q15.36
Dielectrophoretically Aligned GaN Nanowire p-n Junction Diodes.
Sang-Kwon Lee 1 , Tae-Hong Kim 1 , Seung-Yong Lee 1 , Duk-Il Suh 1 , Wook Bahng 2 , Nam-Kyun Kim 2
1 Dept. of Semiconductor Science and Technology, Chonbuk National University, Jeonju Korea (the Republic of), 2 Power Semiconductor Group, Korea Electrotechnology Research Insitute, Changwon Korea (the Republic of)
Show Abstract9:00 PM - Q15.37
Electrical Transport in Vanadium Oxide Nanowires.
Jitae Park 1 , Eunmo Lee 1 , Kyu Won Lee 1 , Cheol Eui Lee 1
1 Physics, Korea University, Seoul Korea (the Republic of)
Show Abstract9:00 PM - Q15.38
Dielectrophoretic Alignment and Fabrication Technique for Realizing GaN Nanowire Devices.
Abhishek Motayed 1 2 , Albert Davydov 1 , Maoqi He 3 , John Melngailis 2 , S. Mohammad 4 3
1 MSEL, Metallurgy, NIST, GAITHERSBURG, Maryland, United States, 2 Dept. of Electrical and Computer Engineering, University of Maryland, College Park, Maryland, United States, 3 Dept. of Electrical and Computer Engineering, Howard University, Washington, District of Columbia, United States, 4 Dept. of Material Science and Engineering, University of Maryland, College Park, Maryland, United States
Show AbstractThe Group IIIA nitrides (binary and ternary alloys of AlN, GaN, and InN) have unique properties such as a direct bandgap spanning the whole solar spectrum (from 0.7 eV for InN to 6.2 eV for AlN), high saturation velocity, and high breakdown electric field. As a result nanostructures and nanodevices made from GaN and related nitrides have great potential for realizing next generation efficient nanoscale UV/visible light emitters, detectors, and gas sensors. We have demonstrated a technique for assembling long (50 µm - 200 µm) GaN nanowires for device applications. These catalyst free nanowires were grown by direct reaction of NH3 and Ga, which resulted in free-standing nanowires along with GaN microplatelets. GaN nanowires were suspended in a solvent using sonication, and using dielectrophoretic forces, nanowires were assembled on prepatterned substrates (SiO2 coated Si and Sapphire) followed by a fabrication sequence to form stable nanowire device structures. The present technique is potentially compatible with CMOS technology and integrating nanodevices with conventional Si microelectronics on the same chip can be made possible with this technique. Only batch fabrication processes like standard photolithography, etching and oxide deposition are used. Calculations have been carried out to reveal the effect of different solvents on the dielectric force factor to better understand the alignment process. Effect of processing conditions on the device yield will be discussed.Present fabrication technique results in the nanowire devices embedded in a passivation layer (SiO2), which have shown to minimize the surface charge effects. Reliable GaN nanowire field effect transistors (FET), with Si substrate as the backgate, have been routinely achieved using this technique. These nanowire FETs do not show any measurable degradation or variation in their electrical characteristics even after extended period of use and/or storage. Field effect mobilities as high as 250 cm2V-1s-1 at 300 K has been measured in these devices. Low temperature transport measurements of these nanowires revealed a correlation between the structural characteristics and electrical properties in these nanowires.
9:00 PM - Q15.39
Theoretical and Experimental Study on Transport Properties of the One-dimensional Electron Gas in an InAlAs/InGaAs Quantum-wire System.
Ilho Ahn 1 , Sung Geun Kim 1 , Jhang W. Lee 2 , Yong Tak Lee 1 , G. Hugh Song 1
1 Information and communication, GIST, Gwangju, Geon-nam, Korea (the Republic of), 2 , Kowon Technology, Yongin, Geonggi-do, Korea (the Republic of)
Show Abstract9:00 PM - Q15.4
Four-Terminal Conductivity Measurement Using PtIr-Coated Carbon Nanotube STM Tips.
Shinya Yoshimoto 1 , K. Kubo 1 , H. Okino 1 , R. Hobara 1 , I. Matsuda 1 , Y. Murata 2 , H. Konishi 2 , M. Kishida 2 , S. Honda 2 , M. Katayama 2 , S. Hasegawa 1
1 Graduate School of Science, the University of Tokyo, Tokyo Japan, 2 Graduate School of Engineering, Osaka University, Osaka Japan
Show AbstractA multi-probe scanning tunneling microscope (STM) is expected to be a very powerful tool for investigating electronic transport properties of nano-materials and -structures [1]. But conventional STM tips, typically 100 nm in radius of curvature at the tip end, are not small enough for the nano-scale measurements because the minimum probe spacing is limited by the size of a tip apex. It was about 200 nm by using conventional STM tips. A carbon nanotube (CNT) tip can be a breakthrough for it, because CNTs have smaller radii and higher aspect ratio. It makes the minimum probe spacing ten times smaller than that by the conventional metal tips. However, it is difficult to control the contact resistance between a CNT and a support metal tip. It scatters from 10 kΩ to 10 MΩ, which prevents stable electrical measurements. We have developed metal-coated CNT tips as conductive probes for transport measurements [2], and investigated their electrical and mechanical characteristics [3]. We have found that PtIr-coated CNT tips have high conductivity (typically less than 10 kΩ) and high mechanical stability.CNT tips used here were fabricated by following procedure. 1) Multi-walled carbon nanotubes, typically 10 nm in diameter, were connected to an electrochemically etched tungsten tip by AC dielectrophoresis [4]. 2) Amorphous carbon was deposited around the contact between the CNT and the tungsten tip by electron beam irradiation in a scanning electron microscope (SEM). 3) The CNT tips were heated in a vacuum chamber. 4) They were wholly coated with a 6-nm thick PtIr thin film by using pulsed laser deposition (PLD) [5].In this research, we have conducted multi-terminal conductivity measurements using these PtIr-coated CNT tips in an independently driven four-tip STM system [1]. We performed four-terminal conductivity measurements on individual Co Silicide nanowires at room temperature [6]. The four-terminal resistance was proportional to the probe spacing between voltage probes, meaning diffusive conduction. The resistivity was 57Ω per μm. Four-terminal resistance at the minimum probe spacing was 1.2Ω, which indicate that the probe spacing was surely reduced to around 20 nm.References:[1] S. Hasegawa, et al., Current Appl. Physics 2, 465 (2002).[2] T. Ikuno, et al., Jpn. J. Appl. Phys. 43, L644 (2003).[3] S. Yoshimoto, et al., Jpn. J. Appl. Phys. 44, L1563 (2005).[4] J. Tang, et al., Adv. Mater 15, 1352 (2003).[5] T. Ikuno, et al., Jpn. J. Appl. Phys. 42, L1356 (2003).[6] H. Okino et al., Appl. Phys. Lett. 86, 233108 (2005).
9:00 PM - Q15.40
In-situ Characterization of Electronic Properties of a Single ZnO Nanowire
Xudong Wang 1 , Jun Zhou 1 , Zhong Wang 1
1 Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractQuasi-one-dimensional (1D) ZnO semiconducting nanostructures, such as nanowires (NWs) and nanobelts (NBs), are considered as an important multi-functional building block for fabricating various nanodevices. Owing to their unique electronic, optical and piezoelectric properties, ZnO NWs/NBs have been successfully applied in FETs, LEDs, laser diodes, sensors, resonators, and piezoelectric devices. Most importantly, ZnO exhibits both semiconducting and piezoelectric properties. The coupling of these two properties endows it with very unique advantages and novel applications [1]. In order to characterize their electronic properties and apply them to nanodevices, we designed an in-situ measuring system inside an SEM chamber, where their I-V characteristics can be examined with a simultaneous observation of their locations and geometrics. In this system, ZnO nanowires were connected to one electrode and located on the SEM stage; while the counter electrode was attached on another independently controlled x-y mechanical stage. Using this set-up, the field emission property of single ZnO NW/NB has been measured under different emission distance. Furthermore, the relationship between the conductance of a single ZnO NW and its bending curvature was identified by connecting the ZnO NW to the counter electrode surface. A decrease of the conductance was observed with increasing the bending curvature by in-situ manipulation and measurements in the SEM chamber. This novel phenomenon is attributed to the unique semiconducting and piezoelectric coupling effect of ZnO, which is different from other semiconductors or carbon nanotubes. These mechanisms realized a new type of nano-device — piezoelectric-field effect transistor (P-FET) composed of a ZnO NW bridging two ohmic contacts, in which the source to drain current is controlled by the bending of the NW. The P-FET has been demonstrated as a force sensor for measuring forces in nano-Newton range and even smaller with the use of smaller NWs.
[1] Z.L. Wang and J.H. Song, Science, 312 (2006) 242-246.
[2] for details: http://www.nanoscience.gatech.edu/zlwang/
9:00 PM - Q15.41
Size-dependent Conductance Behavior of [110] Gold Nanowire.
Kurui Yoshihiko 1 , Oshima Yoshifumi 2 3 , Okamoto Masakuni 4 , Takayanagi Kunio 1 3
1 Condenced Matter Physics, Tokyo Institute of Technology, Meguro, Tokyo, Japan, 2 Matterials Science and Engineerings, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan, 3 , CREST, Japan Science and Technology Corporation, Kawaguchi, Saitama, Japan, 4 Mechanical Engineering Research Laboratory , Hitachi Ltd., Hitachinaka, Ibaraki, Japan
Show Abstract Atomic size metal nanowire(NW) attracts much interest because it shows quantized conductance even at room temperature. Quantized conductance of thin metal NW have been investigated mainly by mechanical cotrollable breaking junction (MCBJ) or scanning tunneling microscope (STM) methods. It has been confirmed that a single atomic strand of gold has a quantized unit of conductance, G0 (G0=2e2/h) and a double strand, two[1]. For gold NWs with conductance bolow 13 - 16G0, the conductance histgram was found to have a periodic peak structure, which was explained by electric shell model. In this model, NW was supposed to be cylindrical wire. On the other hand, for gold NWs above 14-16G0, the conductance histgram had different periodic peak structure, whichi was explained by atomic shell closings model. In this model, the NW was supposed to be crystalline with axis parallel to the [110] direction [2-4]. However, such a stable structure have not been confirmed yet. In this study, we report stable structure of gold NW in the range of conductance from 0 to 50 G0. Using ultra-high-vacuum transmission electron microscope (UHV-TEM) combined with a scanning tunneling microscope (STM), We investigated structure of gold NW simultaneously with conductance. Conductance of NW was measured at 3kHz TEM images were recorded at 30Hz. The stable structure of gold [110]NW was determined by TEM images viewed from two different directions. We found that the stable structure had hexagonal cross-section with wire axis parallel to the [110] direction. We also found that the cross-section had two different symmetries, which has not been point out previously. Such a stable structure was characterized by the number of atomic rows, N, along the wire axis: N=1,3,7,12,19,27,37,48,61,75. Conductance g(N) for each stable NW was determined. The conductance behavior for gold NW above N=37 was explained by atomic shell closing model [3]. In this region, conductance per atomic row was constant (g/N=0.54±0.02). However,conductance behavior below N=37 was not explained by electric shell model [2]. Conductance per atomic row had a tendency to increase with reducing the size (g/N increase from 0.54 to 1.00).Reference:[1] H.Ohnishi, Y.Kondo, and K.Takayanagi, Nature 395, 780 (1998)[2] A.I.Yanson, K.I.Yanson and J.M.van Ruitenbeek Nature 400(London) 144 (1999)[3]A.I.Yanson, K.I.Yanson and J.M.van Ruitenbeek Phys.Rev.Lett 87 216805 (2001)[4]A.I.Mares, A.F.Otte, L.G..Soukiassian, R.H.M.Smit, and J.M.van Ruitenbeek Phys.Rev.B 70 073401 (2001)
9:00 PM - Q15.42
Electrical Conductivity and Optical Properties of Ultra-Thin Gold Nanowires.
Aditi Halder 1 , Bratindranath Mukherjee 1 , Ravishankar Narayanan 1
1 Materials Research Centre, Indian Institute of Science, Bangalore India
Show Abstract9:00 PM - Q15.43
Determination of the Electrical Properties of the Well-Aligned ZnO Nanorods on Si Substrates using AC Impedance Analysis.
Jih-Jen Wu 1 , Daniel Kwan-Pang Wong 1
1 Department of Chemical Engineering, National Cheng Kung University, Tainan Taiwan
Show Abstract9:00 PM - Q15.44
ZnO Nanowire Field-effect Transistor Based on the Edge Defined Lithography.
Hyun-Wook Ra 1 , Sang Hoon Kim 2 , Song Yi Jo 2 , Kwang Sung Choi 2 , Yoon Bong Hahn 2 , Yeon Ho Im 2
1 Semiconductor Physics Research Center, Chonbuk National University, Jeonju, Jeonbuk, Korea (the Republic of), 2 School of Chemical Engineering and Technology and Nanomaterials Processing Research Centre, Chonbuk National University, Jeonju, Jeonbuk, Korea (the Republic of)
Show AbstractZnO nanowires are being widely investigated for applications in electronics, optoelectronics, photovoltaics and sensors. For these applications, the control of the size and location of the nanowires is one of the current challenges to fabricate nanosized patterns. We demonstrate a photolithography-based method for fabricating sub-50 nm ZnO nanowires arrays on a wafer scale instead of the bottom up method. For this work, achieving conformal ZnO ultrathin film by atomic layer deposition will be a key to fabrication of ZnO nanowires by size reduction lithography. The width and height of the nanowires are controlled with nanometer precision, as chip manufacturers now do. The resolution of this method is not limited by photolithography but by the thickness of the material deposited. A further lift-off process is applied to define source-drain electrodes of ZnO nanowire FETs. This work will show the possibility of nanostructured applications composed of ZnO nanowires fabricated by means of lithographic technique.
9:00 PM - Q15.45
Lateral and Vertical Silicon Nanowire Field-Effect Transistors.
Mikael Bjork 1 , Oliver Hayden 1 , Heike Riel 1 , Heinz Schmid 1 , Siegfried Karg 1 , Ute Drechsler 1 , Walter Riess 1 , Volker Schmidt 2 , Stephan Senz 2 , Ulrich Goesele 2
1 , IBM Research GmbH, Ruschlikon Switzerland, 2 , Max Planck Institute, Halle Germany
Show AbstractSemiconducting nanowires have recently attracted considerable attention as the ongoing miniaturization in microelectronics demands new, innovative fabrication techniques and device concepts. Owing to their potential compatibility with existing CMOS technology, silicon (Si) nanowires (NWs) and in particular epitaxially grown Si NWs are considered to be one of the most promising candidates for future logic and memory elements.In the first part of this paper we present our results on lateral Si NW field effect transistors (FETs) based on doped and intrinsic NWs. Our results substantiate the importance of the electrical contacts to the NW FET performance and by using implanted n-contacts we were able to realize individual lateral n-i-n NW FETs which could be operated in inversion mode. In the second part of the paper a generic process flow for fabricating vertical surround-gate field-effect transistors (VS-FET) from epitaxially grown Si nanowires is described and device characteristics are presented. The catalyst for the nanowire growth was patterned by electron beam lithography resulting in well defined arrays of vertical Si nanowires grown on Si (111) substrates. We demonstrate the fabrication processes using n-type silicon nanowires grown on a p-type substrate in ultra-high vacuum using gold as catalyst and silane as precursor gas. The VS-FET fabrication consists of various deposition and etching steps, and has the advantage that no chemical mechanical polishing is required. Moreover, the process can be used to fabricate individual as well as arrays of nanowire VS-FETs. Electrical characterization was carried out on vertical ungated n-doped and p-doped two-terminal devices and gated NW FETs. Single nanowires as well as arrays of about 10^4 nanowires were tested. The measured transistor output- and transfer-characteristics indicate the behavior of an inversion mode driven FET similar to a conventional p-channel MOSFET.
9:00 PM - Q15.46
Carbon/Boron Nitride Nanotube Superlattices.
Serena Povia 1 , Stephanie Reich 1
1 Department of Materials Science and Engineering (DMSE), Massachussets Institute of Technology, Cambridge, Massachusetts, United States
Show Abstract9:00 PM - Q15.47
Chalcogenide Nanowire Devices for Highly Scalable Phase Transition Memory.
Se-Ho Lee 1 , Yeonwoong Jung 1 , Dong-Kyun Ko 1 , Ritesh Agarwal 1
1 Mat. Sci. & Eng., University of Pennsylvania, Philadelphia , Pennsylvania, United States
Show Abstract9:00 PM - Q15.48
Electronic and Optical Properties of SiONWs Grown from a Patterned Reagent: An EELS Study.
Feng Wang 1 2 , Marek Malac 1 2 , Ray Egerton 2 1
1 , National Instiute for Nanotechnology, Edmonton, Alberta, Canada, 2 Department of Physics, University of Alberta, Edmonton, Alberta, Canada
Show Abstract9:00 PM - Q15.49
Fabrication and Electrical Characterization of InGaAs Nanowires by Selective-area MOVPE.
Jinichiro Noboriska 1 , Takuya Sato 1 , Junichi Motohisa 1 , Shinjiro Hara 1 , Takashi Fukui 1
1 Graduate school of Information Science and Technology and Research Center for Integrated Quantum Electronics, Hokkaido University, Sapporo Japan
Show Abstract9:00 PM - Q15.50
Intrinsic Characteristics of Semiconducting Oxide Nanobelt Field-Effect Transistors and Their Applications.
Yi Cheng 1 , Peng Xiong 1 , Lenwood Fields 2 , Jim P. Zheng 2 , Rusen Yang 3 , Zhong Lin Wang 3
1 Physics Department, Florida State University, Tallahassee, Florida, United States, 2 Department of Electrical and Computer Engineering, FAMU/FSU College of Engineering, Tallahassee, Florida, United States, 3 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show Abstract9:00 PM - Q15.51
Ab initio Study of the Electronic Structures and Optical Properties of ZnO Single-wall Nanotubes.
Shelly Elizondo 1 , John Mintmire 1
1 Department of Physics, Oklahoma State University, Stillwater, Oklahoma, United States
Show Abstract9:00 PM - Q15.52
Growth, Structure, and Doping of Gold-Catalyzed Si Nanowires: A First Principles Study.
Soohwan Lee 1 , Kyoung-Eun Kwon 1 , Gyeong Hwang 1
1 Chemical Engineering, The University of Texas at Austin, Austin, Texas, United States
Show Abstract9:00 PM - Q15.53
Ab-initio Study of Erbium Silicide Nanowire Formation on Si (001) Surface.
Tejodher Muppidi 1 , Vidvuds Ozolins 1
1 Material Science and Engineering, University of California Los Angeles, Los Angeles, California, United States
Show Abstract9:00 PM - Q15.54
Single Crystalline Diluted Magnetic Semiconductor Mn:Ge Nanowires.
Tae-Hyun Lee 1 , Han-Kyu Seong 1 2 , Hee-Chul Han 1 , Ryong Ha 1 , Kyeong-Sop Han 2 , Jae-Gwan Park 2 , Heon-Jin Choi 1
1 School of Advanced Materials Science and Engineering, Yonsei University , Seoul Korea (the Republic of), 2 Division of Materials Science and Engineering, Korea Institute of Science and Technology, Seoul Korea (the Republic of)
Show AbstractThe perspective of simultaneously manipulating the charge and spin of a single semiconductor medium leads to the exciting area of spintronics. Among the most promising candidates for such applications is the diluted magnetic semiconductors (DMSs), which transforms spin-frustrated semiconductors to ferromagnets by magnetic doping. Bulk of studies have been done in II-VI and III-V semiconductors and showed ferromagnetism. However, those semiconductors are not compatible with current CMOS processing. A limited study in magnetic doped IV-IV semiconductors, i.e., Si and Ge, has also showed ferromagnetism. However, the polycrystalline nature with many defects in these thin films makes difficult to address and manipulate the ferromagnetism. Meanwhile, semiconductor nanowires have a great potential for addressing the ferromagnetism in DMSs. It is thermodynamically stable features and typically single crystalline with literally defect free. Furthermore, the free standing nature of nanowires open a possibility to determine the intrinsic magnetism of DMS under fully relaxed states. Herein, we report ferromagnetism in single crystalline Mn:Ge nanowires. The nanowires were grown on silicon substrate by using conventional chemical vapor deposition process with aid of catalyst. The nanowires with diameters of 80~100 nm were doped with Mn with amount of c.a., 1%. The X-ray diffraction and transmission electron microscopic characterization showed perfect single crystalline nature without defects and secondary phase inclusions. The superconducting quantum interference device (SQUID) characterization indicates the ferromagnetism in theses nanowires up to room temperature. The x-ray magnetic circular dichroism (XMCD) characterization further showed that the ferromagnetism originates from the doped-, ionic Mn. Along with the electrical properties of nanowires, our results imply that the ferromagnetism is attributed to the long-range ferromagnetic coupling between magnetic ions and delocalized carriers. Based on the experimental results, the ferromagnetism in single crystalline Mn:Ge nanowires will be discussed.
9:00 PM - Q15.55
Freely Suspended Silver Nanowires.
Ray Gunawidjaja 1 2 , Chaoyang Jiang 1 2 , Hyunhyub Ko 1 2 , Sergiy Peleshanko 1 2 , Maryna Ornatska 1 2 , Srikanth Singamaneni 1 2 , Vladimir Tsukruk 1 2
1 Department of Materials Science and Engineering, Iowa State University, Ames, Iowa, United States, 2 School of Materials Science and Engineering , Georgia Institute of Technology, Atlanta, Georgia, United States
Show Abstract9:00 PM - Q15.57
Chemically Functionalized Silicon Nanowires for EWOD Actuation and Matrix-Free Mass Spectrometry Analysis.
Rabah Boukherroub 1 2 , Nicolas Verplanck 2 , Yannick Coffinier 1 2 , Gaëlle Piret 1 2 , Vincent Thomy 2 , Isabelle Fournier 3 , Michel Salzet 3 , Jean-Christophe Camart 2
1 Institut de Recherche Interdisciplinaire (IRI), CNRS, Villeneuve d'Ascq France, 2 Institut d'Electronique, de Microélectronique et de Nanotechnologie, CNRS, Villeneuve d'Ascq France, 3 Laboratoire de Neuroimmunologie des Annélides, Université Lille1, Villeneuve d'Ascq France
Show Abstract9:00 PM - Q15.58
Debundling by Dilution: Observation of Large Populations of Individual MoSI Nanowires in High Concentration Dispersions.
Valeria Nicolosi 1 , Damjan Vengust 2 , Dragan Mihailovic 2 3 , Werner Blau 1 , Jonathan Coleman 1
1 School of Physics, Trinity College Dublin, Dublin Ireland, 2 , Jozef Stefan Institute, Ljubljana Slovenia, 3 , Mo6, Ljubljana Slovenia
Show Abstract9:00 PM - Q15.59
Nanorods of the Concentrated Ferromagnetic Semiconductor EuO: Synthesis and Physical Properties.
Matthew Bierman 1 , Song Jin 1
1 , University of Wisconsin-Madison, Madison, WI, Wisconsin, United States
Show Abstract9:00 PM - Q15.6
Tunneling Electron Transport of Silicon Nanochains Studied by in-situ Scanning Electron Microscopy.
Hideo Kohno 1 , Seiji Takeda 1
1 , Osaka University, Toyonaka, Osaka, Japan
Show AbstractElectron transport and field emission properties of one dimensional materials such as nanowires and nanotubes have been studied intensively. We report electron transport properties of silicon nanochains, in which silicon nanoparticles are covered with and connected alternately by oxide forming periodically-heterostructured nanowires [Kohno and Takeda, Appl. Phys. Lett. 73, 3144 (1998)., Kohno and Takeda, e-J. Surf. Sci. Nanotech. 3, 131 (2005)], measured at high bias voltages up to 120 V. I-V curves are measured in-situ using a micro-manipulator in a scanning electron microscope (SEM). Thus, the distance between silicon nanochains and the microprobe can be controlled under SEM observation. The molybdenum substrate on which silicon nanochains are grown is grounded and the tungsten microprobe is positively biased. We observe significant current increase at the bias voltages of several tens of volts when the microprobe is both separated by about 1 micrometer and attached to silicon nanochains. Fowler-Nordheim (FN) plots of the I-V data above 100 V show that the transport properties of silicon nanochains at such high bias voltages can be described well by the FN law. Accordingly, we conclude that the field-induced tunneling current is dominant even when the microprobe is attached to silicon nanochains. Our results suggest a possible application of Si nanochains to cold electron emitters.
9:00 PM - Q15.60
Piezoelectric Versus Carbon Nanotube Actuators.
Hossein Golnabi 1 , Amir Nikjo 1 , Afshin Asadpour 1 , Mahmod Ghorannevis 1
1 , Islamic Azad University, Tehran Iran (the Islamic Republic of)
Show Abstract9:00 PM - Q15.7
Electronic and Mechanical Properties of Super Carbon Nanotube Networks.
Vitor Coluci 1 , Socrates Dantas 2 , Ado Jorio 3 , Douglas Galvao 1
1 Applied Physics, State University of Campinas, Campinas, Sao Paulo, Brazil, 2 Physics Department, Federal University of Juiz de Fora, Juiz de Fora , Minas Gerais, Brazil, 3 Physics Department, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
Show Abstract9:00 PM - Q15.8
Three-way Electrical Gating Characteristics of Metallic Y-junction Carbon Nanotubes.
Jeongwon Park 1 , Prabhakar Bandaru 1 , Apparao Rao 2
1 Materials Science and Engineering Program, University of California, San Diego, La Jolla, California, United States, 2 Department of Physics and Astronomy, Clemson University, Clemson, South Carolina, United States
Show Abstract9:00 PM - Q15.9
Defect Induced Enhancement of Carrier Transport in Individual Multiwalled Carbon Nanotubes and their Networks.
Saurabh Agrawal 1 , Makala Raghuveer 1 , Rampi Ramprasad 2 , Ganapathiraman Ramanath 1
1 Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States, 2 Department of Materials Science and Engineering & Institute of Materials Science, University of Connecticut, Storrs, Connecticut, United States
Show Abstract
Symposium Organizers
Prabhakar Bandaru University of California-San Diego
Morinobu Endo Shinshu University
Ian Kinloch University of Cambridge
Apparao M. Rao Clemson University
Q16: Thermal Properties & Energy Storage
Session Chairs
Thursday AM, November 30, 2006
Room 312 (Hynes)
9:00 AM - Q16.1
In-Situ TEM Thermoelectric Property Measurements of Nanowires and Carbon Nanotubes.
Tom Harris 1 , Chris Dames 1 , Shuo Chen 2 , Zhifeng Ren 2 , Millie Dresselhaus 3 4 , Gang Chen 1
1 Mechanical Engineering, MIT, Cambridge, Massachusetts, United States, 2 Physics, Boston College, Chestnut Hill, Massachusetts, United States, 3 Electrical Engineering, MIT, Cambridge, Massachusetts, United States, 4 Physics, MIT, Cambridge, Massachusetts, United States
Show Abstract9:15 AM - Q16.2
Thermal Transport in MWNT Sheet.
Ali Aliev 1 , Mei Zhang 1 , Shaoli Fang 1 , Anvar Zakhidov 1 , Ray Baughman 1
1 NanoTech Institute, University of Texas at Dallas, Richardson, Texas, United States
Show AbstractWe present the comparative study of the anisotropic thermal conductivity and the thermal diffusivity of highly oriented free standing multiwalled carbon nanotube (MWNT) sheet using two techniques: laser flash and self-heating 3ω methods. The highly aligned transparent nanotube sheet was drawn from a sidewall of MWNT forest synthesized by chemical-vapor deposition. The thermal conductivity and the thermal diffusivity along the alignment are 50±5 W/Km and 45±5 mm2/s respectively and mostly deteriorated by intrinsic defects of individual nanotubes and phonon-phonon interaction in bundles formed the supporting matrix of MWNT sheet. Long overlapping tube-tube interconnections do not dominate in electron and phonon transport. The extremely high surface area of MWNT sheet leads to the excessive radial radiation of the heat and dose not allow to transfer the heat energy by means of phonons to distances more than 2 mm. On the other hand the high surface area and negligible heat capacitance make it perfect material for bolometric sensing (S=26 V/W) and heat dissipation.
9:30 AM - Q16.3
Dependence of the Raman Spectrum of Silicon Nanowires on the Wire Environment.
Harald Scheel 1 , S. Reich 2 , A. Ferrari 3 , M. Cantoro 3 , A. Colli 3 , C. Thomsen 1
1 Institut für Festkörperphysik, Technische Universität Berlin, Berlin Germany, 2 Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 3 Department of Engineering, University of Cambridge, Cambridge United Kingdom
Show Abstract9:45 AM - Q16.4
Carbon Nanotube-Enhanced Carbon-Phenenolic Ablator Material.
Pavel Nikolaev 1 , Mairead Stackpoole 3 , Wendy Fan 4 , Brett Cruden 4 , Mike Waid 2 , Padraig Moloney 2 , Sivaram Arepalli 1 , James Arnold 4 , Harry Partridge 5 , Leonard Yowell 2
1 , ERC Inc./NASA-JSC, Houston, Texas, United States, 3 , Eloret Corporation / NASA-ARC, San Jose, California, United States, 4 University Affiliated Research Center, University of California Santa Cruz / NASA-ARC, Santa Cruz, California, United States, 2 , NASA-JSC, Houston, Texas, United States, 5 , NASA-ARC, San Jose, California, United States
Show AbstractPhenolic impregnated carbon ablator (PICA) is a thermal protection system (TPS) material developed at NASA Ames Research Center in the mid-90’s for Discovery missions. It was used on the Stardust return capsule heat shield which successfully executed the highest speed Earth entry to date on Janurary 15, 2006. PICA is a porous fibrous carbon insulation infiltrated with phenolic resin, and is an excellent ablator that is effective for heating rates up to 1000 W/cm2. It is one of several candidate TPS materials for the next generation of crewed spacecraft for Lunar and Mars missions.We will describe an ongoing research effort at NASA to improve mechanical properties of the phenolic matrix with carbon nanotubes. The aim is two-fold: to increase overall TPS strength during reentry and to improve Micrometeoroid / Orbital Debris (MMOD) protection in space. The former requires at least a good dispersion of nanotubes in phenolic, while the latter also requires covalent bonding between them to couple and transfer impact energy effectively from matrix to nanotubes. We will discuss the required chemical functionalization of nanotubes, processing issues and test results.
10:00 AM - Q16.5
Carbon Nanotube as Loading Component to Efficiently Lower the Freezing Point in the 50% Water /50% Anti-freezing Coolant or Ethylene Glycol System.
Haiping Hong 1 , Jesse Wensel 1 , Walter Roy 2
1 Material and Metallurgical Engineering, South Dakota School of Mines and Technology, Rapid City, South Dakota, United States, 2 , Army Research lab, Arbdeen , Maryland, United States
Show AbstractIn this abstract, we report, for the first time, the effect of the lowered freezing point in the 50% water / 50% anti-freeze coolant (PAC) or 50% water / 50% ethylene glycol (EG) by adding the carbon nanotube particle. The experimental results indicated that nano material are much more efficient (hundreds fold) in lowering the freezing point than the regular ionic material (e.g. NaCl). The possible explanation to this interesting phenomenon is the colligative property of fluid and relative small size of nano material. It is quite certain that the carbon nanotube could be the wonderful candidate for the nano coolant application because it could not only increase the thermal conductivity, but also efficiently low the freezing point.
10:15 AM - Q16.6
Inorganic Nanotubes for Energy Storage: An Ab Initio Study.
Kevin Tibbetts 1 , Caetano Miranda 1 , Ying Meng 1 , Gerbrand Ceder 1
1 Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show Abstract10:30 AM - Q16.7
Vertically Aligned Carbon Nanofibers for Energy Storage Applications.
Kiu-Yuen Tse 1 , Viacheslav Dementiev 1 , Lingzhi Zhang 1 , Sarah Baker 1 , Patrick Warf 1 , Robert West 1 , Robert Hamers 1
1 Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States
Show AbstractVertically-aligned carbon nanofibers (VACNFs) are interesting materials for applications such as energy storage because the vertical alignment provides excellent accessibility to ions, while the direct electrical contact to each nanofiber provides very low resistance. We have investigated the electrical properties of VACNF forests in aqueous and non-aqueous electrolytes and characterized the effective resistance, capacitance, and electron-transfer rates. We demonstrate that by combining VACNFs with organosilicon-based electrolytes, it is possible to fabricate supercapacitors that exhibit high capacitance, excellent electrical stability, and good frequency response. The exceptionally good electrical stability of the organosilicon electrolytes allows extended voltage range compared with aqueous and/or alkyl carbonate electrolytes. The vertical orientation of the nanofibers provides excellent ionic accessibility and low resistance, which translate to good high-frequency response when used in energy storage devices. We will also discuss effects of chemical modification with molecular monolayer on the electrode surface, nanofiber aggregation, and further experiments to improve the performance of VACNFs electrodes.
10:45 AM - Q16.8
Lithium Capacity and Electrochemical Performance of Boron Doped Single Wall Carbon Nanotubes.
Thomas Gennett 1 3 , R. Morris 2 , Jeffrey Blackburn 3 , Brett Gall 2 , Brian Dixon 2 , Michael Heben 3
1 Chemistry, Rochester Institute of Technology, Rochester, New York, United States, 3 , National Renewable Energy Laboratory, Golden, Colorado, United States, 2 , Phoenix Innovation, West Wareham, Massachusetts, United States
Show AbstractFuture portable power requirements will demand greater specific energy and power from lithium batteries. To meet these goals, new battery technology needs to be developed that delivers increased performance in addition to high peak or pulse power. Single wall carbon nanotube materials were directly synthesized under conditions that achieved up to 2% boron integration into the nanotube backbone . Several recent reports have described B doping as a means of increasing the capacity of CNT materials. It is predicted that the coulombic efficiency of the Li+ discharge from the tubes can be increased to more than 90%, thereby dispelling the tendency for the large hysteresis in capacity normally seen in CNT materialsInitial testing was performed with a standard two electrode polypropylene test cell fitted with two stainless steel piston-type electrodes (~1cm^2 area). A test cell was assembled using the B-doped material as the anode. In standard 1M LiIM: 50:50 EC:EMC electrolyte, the material was lithiated and cycled. Interestingly the performance improved with successive cycling till after 10 cycles an average specific energy of >800 mAh/g based on the total mass of the electrodes was observed. The complete characterization of the Boron-doped carbon nanotube materials along with direct comparison to other nantube and standard MCMB electrodes will be presented.
Q17: Nanowires and Nanotube Photonics
Session Chairs
Thursday PM, November 30, 2006
Room 312 (Hynes)
11:30 AM - **Q17.1
Nanowire Photonics.
Peidong Yang 1 , Peter Pauzauskie 1
1 Chemistry, University of California at Berkeley, Berkeley, California, United States
Show Abstract12:00 PM - **Q17.2
Carbon Nanotube Transistors and their Interaction with Light.
Marcus Freitag 1
1 , IBM Watson Research Center, Yorktown Heights, New York, United States
Show AbstractSemiconducting carbon nanotubes can make very small and fast electrical switches. They are also optically remarkable: Each nanotube chirality possesses its own fingerprint in its absorption and emission bands as well as in its Raman-active vibrations. In addition, the extreme confinement of electrons and holes in a carbon nanotube leads to strong exciton interactions and most of the oscillator strength goes to these excitons instead to the band-to-band transitions. We use the transistor geometry to probe the optical interactions in individual carbon nanotubes. Absorption of photons leads to photoconductivity and electrical excitation leads to the emission of infrared light. The spatial and spectral distributions of these are the focus of this talk. In collaboration with James Tsang, Jia Chen, Xiaohui Qiu, Vasili Perebeinos, John Kirtley, and Phaedon Avouris.
12:30 PM - Q17.3
Optical Scanning and Integration of Subwavelength Semiconductor Nanowires.
Peter Pauzauskie 1 2 , Aleksandra Radenovic 3 4 , Jan Liphardt 3 4 , Yuri Nakamura 1 , Peidong Yang 1 2
1 Department of Chemistry, UC Berkeley, Berkeley, California, United States, 2 Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 3 Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 4 Department of Physics, UC Berkeley, Berkeley, California, United States
Show Abstract12:45 PM - Q17.4
Electric Field Quenching of Carbon Nanotube Fluorescence.
Anton Naumov 1 , Dmitri Tsyboulski 2 , Sergei Bachilo 2 , R. Bruce Weisman 2
1 Physics, Rice University, Houston, Texas, United States, 2 Chemistry, Rice University, Houston, Texas, United States
Show AbstractQ18: Photonic Applications and Phenomena II
Session Chairs
Thursday PM, November 30, 2006
Room 312 (Hynes)
2:30 PM - **Q18.1
Progress in Transparent, Conductive, Carbon Nanotube Thin Films.
Andrew Rinzler 1 , John Reynolds 2 , Zhuangchun Wu 1 , Bo Liu 1 , Rajib Das 1
1 Physics, University of Florida, Gainesville, Florida, United States, 2 Chemistry, University of Florida, Gainesville, Florida, United States
Show AbstractResearch activity in thin, transparent and electrically conductive, pure nanotube (no binder) films has accelerated dramatically since we first described their membrane based fabrication and transfer methods [Z. Wu, Z. Chen, X. Du, J. M. Logan, J. Sippel, M. Nikolou, K. Kamaras, J. R. Reynolds, D. B. Tanner, A. F. Hebard, A. G. Rinzler, Science 305, 1273 (2004)]. Already demonstrated (by ourselves and others) is their utility as transparent electrodes in photovoltaic, electrochromic and light emitting devices, as well as their application in thin film transistors and hydrogen sensors. Optimization of the performance in these and other applications, accessing the benefits of the high surface area, the lack of electromigration and a tunable workfunction is the present challenge. We will describe both the present state of progress and some limitations. We will also describe recently developed, novel techniques to 1) pattern the films, and to 2) increase their accessible surface area, both of which should prove highly useful going forward.
3:00 PM - Q18.2
Auger Recombination and Many-Body Interactions of Excitons in Single-Walled Carbon Nanotubes.
Libai Huang 1 , Todd Krauss 1
1 Chemistry, University of Rochester, Rochester, New York, United States
Show Abstract3:15 PM - Q18.3
Non Exponential and Non-local Blinking Kinetics of CdSe Nanowires.
Vladimir Protasenko 1 , Darren Peterson 1 , Masaru Kuno 1
1 Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States
Show Abstract3:30 PM - Q18.4
Absorption Cross-Sections and Fluorescence Quantum Yields of Structure-Selected Single-Walled Carbon Nanotubes (SWNTs) Quantified with Near-IR Fluorescence Microscopy.
Dmitri Tsyboulski 1 , John-David Rocha 1 , Sergei Bachilo 1 , R. Bruce Weisman 1
1 Chemistry, Rice Universtiy, Houston, Texas, United States
Show AbstractDiscovery of SWNTs near-IR fluorescence and subsequent spectral assignment of SWNTs excitation/emission features to particular (n,m)-structures provided a simple and powerful spectrofluorimetric technique to analyze SWNTs structural composition in bulk samples. However, quantification is hampered by the lack of experimental data on such photophysical parameters as absorption cross-sections and fluorescence quantum yields of specific nanotube (n,m)-types.Here we utilize near-IR fluorescence microscopy and spectroscopy of individual semiconducting nanotubes to determine the product of their absorption cross-section σ and fluorescence quantum yield Φ. We observe “long” individual nanotubes with well-resolved spatial dimensions in a thin aqueous film using near-IR fluorescence microscopy and measure their emission spectra to find the nanotube’s (n,m) identity. Nanotube samples are excited with circularly polarized laser beams at 658 and 785 nm. We select only nanotubes whose E22 transitions are nearly resonant with the excitation laser.In general, the detected fluorescence power P from a single nanotube is described as P = α(λ11)*( λ22/λ11)*FEXC (λ22)*σ (λ22)*Φ, where α(λ11) is the collection efficiency of an optical system at the emission wavelength λ11 and FEXC (λ22) is the excitation flux. We carefully measure the excitation flux at the target, the detected fluorescence power and the collection efficiency of our experimental system. The deduced product of the SWNT absorption cross-section and the quantum yied varies from 10-14 to 10-15 cm2 per μm of length for the different (n,m)-types. We note that available experimental estimates from bulk measurements give SWNTs absorption cross-sections of ca. 10-13 cm2 per μm and quantum yields of ca. 10-3. Our experimental data suggest that parameters of single SWNTs may differ substantially from these prior bulk estimates. Specific experimental findings as a function of nanotube structure will be presented and discussed.
3:45 PM - Q18.5
Characterization of Carbon Nanotube Electrodes for Organic Optoelectronic Applications.
Carla Aguirre 1 2 , Patrick Desjardins 1 2 , Richard Martel 3 2
1 Département de génie physique, École Polytechnique de Montréal, Montréal, Quebec, Canada, 2 , Regroupement québécois sur les matériaux de pointe, Montréal, Quebec, Canada, 3 Département de chimie, Université de Montréal, Montréal, Quebec, Canada
Show AbstractQ19: Characterization and Optical Properties of Nanowires
Session Chairs
Thursday PM, November 30, 2006
Room 312 (Hynes)
4:30 PM - Q19.1
Composition Analysis of Single Si Nanowires Using Pulsed Laser Atom Probe Tomography.
Daniel Perea 1 , Eric Hemesath 1 , Jessica Lensch 1 , Lincoln Lauhon 1
1 Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States
Show Abstract4:45 PM - Q19.2
Single Walled Carbon Nanotube Analysis by Photoluminescence and Raman Microscopy: Rapid, Robust Acquisition and Simulation of Quantum and Chiral Maps to Ease Structural Assignments.
Adam Gilmore 1 , Fran Adar 1 , Eunah Lee 1 , Ray Kaminski 1 , Andrew Whitley 1
1 , Horiba Jobin Yvon, Edison, New Jersey, United States
Show Abstract5:00 PM - Q19.3
Direct Observation of the Optical Near-field Energy Transfer Among the Resonant Energy States Between ZnO Nanorod Double-quantum-well Structures.
Takashi Yatsui 1 , Suguru Sangu 2 , Tadashi Kawazoe 1 , Motoichi Ohtsu 3 1 , Jinkyoung Yoo 4 5 , Sung Jin An 4 5 , Gyu-Chul Yi 4 5
1 SORST, JST, Machida Japan, 2 Advanced Technology R&D Center, Ricoh Co., Ltd., Yokohama, Kanagawa, Japan, 3 School of Engineering, University of Tokyo, Bunko-ku, Tokyo, Japan, 4 Department of Materials Science and Engineering, POSTECH, Pohang, Gyungbuk, Korea (the Republic of), 5 , National CRI Center for Semiconductor Nanorods, Pohang, Gyungbuk, Korea (the Republic of)
Show Abstract5:15 PM - Q19.4
Growth and Characterization of GeO2 Nano- and Microwires with Lightguiding Behaviour.
Pedro Hidalgo 1 , Bianchi Mendez 1 , Javier Piqueras 1
1 Materials Physics, Universidad Complutense de Madrid, Madrid Spain
Show Abstract5:30 PM - Q19.5
TiO2 Nanotubes: Synthesis, Characterisation And Application.
Dominik Eder 1 2 , Winfried Jochum 2 , Ian Kinloch 1 , Reinhard Kramer 2 , Alan Windle 1
1 Department of Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom, 2 Institute of Physical Chemistry, University of Innsbruck, Innsbruck Austria
Show AbstractTitanium dioxide (TiO2) is among the most important oxide based materials with applications in photochemical, catalytical and electrochemical technologies, and the fabrication of nanostructured and especially nanoporous products is a key challenge. Of the two important phases of TiO2, anatase is kinetically favoured over rutile, which is thermodynamically stable. There is strong evidence that rutile would be favoured over other types of titania in terms: of selectivity and improved kinetics in photochemical reactions [1], of dielectric constant [2,3] and of refractive index for photo-electronic applications [3]. There have been some attempts to produce anatase and tri-titanate nanotubes [4-6]; hitherto there are no reports on the successful synthesis of titania nanotubes with a rutile phase.In this work we produced TiO2 nanotubes with either the anatase or the rutile phase involving the sol-gel route using sacrificial carbon nanotubes as templates, with subsequent heat treatment to convert the templated anatase to rutile [7]. The carbon nanotubes support the structure during phase transformation and can furthermore be used to control the internal diameter of the rutile nanotubes, while synthesis conditions control the wall thickness. The rutile nanotubes are stable up to 700 C and exhibit very high specific surface areas (up to 120 m2/g) that favour them for use in applications including photo-catalysis and catalyst support.The applied characterization tools include SEM, (HR)TEM, electron tomography, XRD, FTIR and Raman spectroscopy. For use as catalyst support we measured the stability of the TiO2 nanotubes versus a thermal treatment in H2 suitable for a typical catalytic pre-treatment by thermal analysis (TGA/DSC) and controlled sintering (BET). The photochemical properties were studied by UV/VIS and photoluminescence during the decomposition of organic compounds (e.g. salicyl acid). The catalytic performance of the TiO2 nanotubes and their supporting ability for platinum and gold was tested for the hydrogenation of CO and hydrogenolysis of MCP, with special focus on the SMSI effect (Strong Metal-Support Interaction [8]).1)O. Carp, C.L. Huisman, A. Reller, Prog. Solid State Chem. 32, 33-177 (2004)2)D. Eder, R. Kramer, J. Phys. Chem. B, 108(39), 14823-29 (2004)3)U. Diebold, Surf. Sci. Rep. 48, 53 (2003)4)T. Kasuga, M. Hiramatsu, A. Hoson, T. Sekino, K. Niihara, Adv. Mater. 11 (15), 1307-1311 (1999)5)O. K. Varghese, D. Gong, M. Paulose, K.G. Ong, E.C. Dickey, C.A. Grimes, Adv. Mater. 15 (7-8), 624 (2003)6)G. Armstrong, A.R. Armstrong, J. Canales, P. G. Bruce, Chem.Commun. 21 (19), 2454-6 (2005)7)D. Eder, I.A. Kinloch, A.H. Windle, Chem. Commun. 16 1448-1450 (2006)8)S. J. Tauster, S. C. Fung,R. L. Garten, J. Am. Chem. Soc., 100, 170 (1978)
5:45 PM - Q19.6
ZnSe Nanorings and their Cathodoluminescence.
Lei Jin 1 2 , Yp Leung 1 , Wallace Choy 1 , Jianbo Wang 2 , Ti Yuk 1
1 Department of Electrical & Electronic Engineering, the University of Hong Kong, Hong Kong Hong Kong, 2 Physics, Wuhan University, Wuhan China
Show AbstractZinc-based II-VI compound semiconductors have already been utilized in a wide range of applications and zinc selenide (ZnSe) is an attractive candidate for IR optics, optoelectronic and microelectronic devices. Recently, various types of one dimension (1-D) ZnSe nanostructures have been fabricated such as nanowires, nanorods, nanobelts and nanorings. The growing mechanisms and optical properties of the 1-D ZnSe nanostuctures have been discussed. Most of the ZnSe nanostructures are stable zinc blende structures. However, wurtzite ZnSe is metastable phase and there are limited reports on wurtzite ZnSe nanostructures. In this report, we will investigate the wurtzite ZnSe nanorings and nanobelts.The nanostructures were grown through tube furnace using ~0.5g ZnSe powder (99.99% Sigma Aldrich) in an alumina boat placed at the center of the furnace. The temperature at the center was increased to 950oC and the carrier gas was 95% Ar mixed with 5% H2. The substrate was Au (~5nm) coated Si. Our results show that wurtzite ZnSe nanorings can be synthesized by reducing the pressure of the chamber below 5 Torr or increasing the temperature of the substrate to 700oC through increasing the growth time to 90 minute. The nanostructures were characterized by EDS, SAED, SEM and TEM. The results confirm that the nanostructures are wurtzite ZnSe nanorings and nanobelts. The effects of the growth temperature and the reactor pressure to the formation of the wurtzite phase will be discussed. The wurtzite ZnSe structures can be understood by the favourable nucleation of the metastable wurtzite phase under the Ostwald’s step rule. The growth mechanism of the nanorings will also be investigated. The cathodolumiescence of the ZnSe nanorings with the bandedge transition peak and broad emission at lower energy has been obtained.
Q20: Poster Session: Thermal, Optical and Mechanical Properties and Applications: Biological Interactions
Session Chairs
Prabhakar Bandaru
Morinobu Endo
Ian Kinloch
Apparao Rao
Friday AM, December 01, 2006
Exhibition Hall D (Hynes)
9:00 PM - Q20.1
Self-Assembled Conductive Network of Carbon Nanotubes nn Polyaniline Forming Potential Nanocomposites.
Sanju Gupta 1 , Vincent Kandagor 1 , Rishi Patel 1 , Yiwei Ding 2 , Robert Hauge 3
1 Physics and Materials Science, Missouri State University, Springfield, Missouri, United States, 2 , Crosslink Inc, Saint Louis, Missouri, United States, 3 Chemistry, Rice University, Houston, Texas, United States
Show AbstractCarbon nanotubes (CNTs) are of great interest because of several unsurpassable physical (mechanical, electrical, thermal, and chemical) properties. Especially their large elastic modulus and breaking strength make them highly attractive for their use as reinforced agents in forming a new class of multifunctional advanced materials - nanocomposites, in addition to high conductivity (either in semiconducting or metallic regimes) achieved through lower percolation thresholds for several electronic applications. Among the known conducting polymers, polyaniline (PANI) has a high potential due to its ease of synthesis, excellent environmental, and thermal stability and reversible control of its electrical/electronic properties. In this work, PANI-single-/multiwalled NTs composites films containing different nanotube content of both kinds were synthesized by spin-cast preceded by ultrasonic mixing of the constituents. They were characterized using complementary techniques including scanning electron microscopy, X-ray diffraction, infrared and Raman spectroscopy, and conductivity revealing their microscopic structure and physical properties thus helping in establishing process-structure-property correlations. The present work will discuss some of these findings in terms of a) self-alignment of nanotubes in conducting polymer b) their optical and electrical properties, and c) their design with a view to electronic and sensor applications, all ascribed due to long range pi-pi interaction between the constituents. *This work is supported by internal funds.
9:00 PM - Q20.11
Electroactive Carbon Nanotube Nanocomposites for Sensors and Actuators
Jin Ho Kang 1 4 , Cheol Park 1 4 , Amy Brazin 2 , James High 3 , Sharon Lowther 4 , Harrison Harrison 4
1 , National Institute of Aerospace, Hampton , Virginia, United States, 4 AMPB, NASA LaRC, Hampton , Virginia, United States, 2 Aeronautics and Astronautics Engineering, MIT, Cambridge, Massachusetts, United States, 3 TDIB, NASA LaRC, Hampton , Virginia, United States
Show AbstractRecent studies of carbon nanotube-polyimide nanocomposites indicate that these materials have the potential to provide the combination of structural integrity and sensing or actuation capability. Very small loadings of single wall carbon nanotubes, approximately 0.05 to 0.1wt%, in high performance polymer matrices result in electroactive sensor materials which respond to strain, stress, pressure, and temperature. These materials also exhibit significant electroactive strains in response to applied electric fields. Out of plane strains as large as 2.6% have been observed for relatively low applied fields (< 1 MV/m). In order to investigate the mechanism of electroactive strain, the dielectric constant and elastic modulus of the nanocomposites were measured. This presentation will highlight the electroactive characteristics of these carbon nanotube-polyimide nanocomposites and discuss their potential application for multifunctional structural applications.
9:00 PM - Q20.12
Preparation of Nanocomposite Carbon Fiber with Functionalized Single Wall Carbon Nanotube.
Bo Yi 1 , Ramakrishnan Rajagopalan 2 , Henry Foley 1 2 3
1 Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States, 2 Material Research Institute, Pennsylvania State University, University Park, Pennsylvania, United States, 3 Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania, United States
Show AbstractA nanocomposite carbon fiber was prepared by doping single wall carbon nanotube (SWNT) in a carbonizable polymer, poly (furfuryl alcohol) (PFA), followed with pyrolysis. To overcome the weak interaction between the SWNT and polymer, the SWNT was first functionalized with arylsulfonic acid groups on sidewall to obtain good compatibility with PFA. HRTEM imaging also shows that the SWNT bundles are exfoliated after functionalization. Once this state of the SWNTs was accomplished, the PFA-functionalized SWNT (PFA-SWNT) was prepared by in situ polymerization of furfuryl alcohol (FA). The sulfonic acid groups on the surface of the SWNT acted as catalyst for FA polymerization and the resulting PFA then grafted to the SWNTs. The remaining FA is polymerized with p-toluenesulfonic acid. An SWNT/PFA composite fiber was prepared by templating the PFA-SWNT and PFA in a capillary tube and then thermosetting it. After pyrolysis in argon at 800°C, a nanocomposite carbon fiber was generated. HRTEM images and tensile modulus are taken to characterize this composite carbon.
9:00 PM - Q20.13
Micromachined Silicon Grids for Direct TEM Characterization of Carbon Nanotubes Grown by CVD.
Yongho Choi 1 , Jason Johnson 1 , Ryan Moreau 1 , Eric Perozziello 2 , Ant Ural 1
1 Electrical and Computer Engineering, University of Florida, Gainesville, Florida, United States, 2 , Stanford Nanofabrication Facility, Stanford, California, United States
Show Abstract9:00 PM - Q20.14
Study on the Synthesis of CNTs and the Fabrication of CNTs-Based MEA for DMFC Application.
Chun-Hsi Su 1 , Chii-Ruey Lin 1 , Hsin-Chin Hung 1
1 Institute of Manufacturing Technology, National Taipei University of Technology, Taipei Taiwan
Show AbstractA fuel cell (FC) generates electricity by chemical reactions. The catalyst dispersion in membrane electrode assembly (MEA) of FC is a crucial factor to affect the performance of the cell. A novel grafting method is adopted in this study to grow secondary carbon nano-tubes (CNTs) on a substrate comprised of primary CNTs, in order to form branchy CNTs with higher specific surface area (SSA). The as-obtained branchy CNTs are then used as catalyst, Pt, carriers in the MEA of direct methanol fuel cell (DMFC). A self-assembled DMFC of air-breathing type with active MEA area of 2 x 2 cm2 is used in this study as the standard FC for the electrical performance test. The peak power of DMFC comprised of an MEA with sole primary CNTs is 0.002 watts at 0.15 V. Such peak power can be increased up to 0.01 watts at 0.4 V for the replaced MEA with new branchy CNTs. The open circuit voltages (OCVs) are 0.4 V and 0.6 V for DMFCs with MEAs of sole primary CNTs and branchy CNTs, respectively. Furthermore, the patterns of CNTs was designed to provide micro-channels of fuel. The pattern growth of CNTs have been fabricated by selective area growth method in this research.
9:00 PM - Q20.15
Novel Functional Nanocomposites based on Filled Single-walled Carbon Nanotubes.
Andrey Eliseev 1 , Marina Chernysheva 1 , Alexey Lukashin 1 , Yuri Tretyakov 1 , Sergey Savilov 2 , Nikolay Kiselev 3 , Olga Zhigalina 3 , Andrey Kumskov 3 , Anatoly Krestinin 4 , John Hutchison 5
1 Dept. of Materials Science, Moscow State University, Moscow Russian Federation, 2 Department of Chemistry, Moscow State University, Moscow Russian Federation, 3 , Institute of Crystallography, Moscow Russian Federation, 4 , Institute of Problems of Chemical Physics, Chernogolovka Russian Federation, 5 Department of Materials, University of Oxford, Oxford United Kingdom
Show Abstract9:00 PM - Q20.16
Novel Composites and Devices Based on Polymer-Free Carbon Nanotube Fibers.
Mikhail Kozlov 1 , David Novitski 1 , Jiyoung Oh 1 , Ryan Capps 1 , Ernest Kozlov 1 , Kailing Cai 1 , Semen Abramov 1 , Theja Lanka 1 , Ray Baughman 1
1 NanoTech Inst., Universty of Texas at Dallas, Richardson, Texas, United States
Show Abstract9:00 PM - Q20.17
Covalent Bond Formation in Defected Nanopeapods Induces Local Deformations on Nanotube Walls.
Takashi Yumura 1 , Miklos Kertesz 1
1 Department of Chemistry, Georgetown University, Washington , District of Columbia, United States
Show Abstract9:00 PM - Q20.18
Strain-based Electrical Properties of Systems of Carbon Nanotubes Embedded in Parylene.
Jon Brame 1 , Johnathan Goodsell 1 , Stephanie Getty 2 , David Allred 1
1 Physics and Astronomy, Brigham Young University, Provo, Utah, United States, 2 Materials Engineering Branch, Code 541, NASA -- Goddard Space Flight Center, Greenbelt, Maryland, United States
Show Abstract9:00 PM - Q20.19
The Role of Twinning in Shape Evolution of Anisotropic Noble Metal Nanostructures.
Miguel Jose Yacaman 1 , Jose Luis Elechiguerra 1 , Jose Reyes 2
1 Chemical Engineering, University of Texas at Austin, Austin, Texas, United States, 2 Instituo de Fisica, Universidad Nacional Autonoma de Mexico, Mexico, D.F., Mexico, D.F., Mexico
Show AbstractNanotechnology provides the ability to engineer the properties of materials by controlling their size and shape. Among the most interesting nanostructures are anisotropic noble metal nanocrystals such as nanorods and nanowires. Nevertheless, the production of such crystals in a controlled fashion remains as a challenging task and many available colloidal techniques produce a mixture of morphologies. In cases where high yields of a particular anisotropic structure have been produced, the growth mechanism has been primarily explained in terms of the presence of surfactants or capping agents that regulate the growth of the crystal in a particular direction. Although, it is interesting that nearly identical shapes and habits tend to appear from radically different synthesis methods, even without the use of surface modifying agents. Then, the growth mechanism should also consider nucleation and kinetics, and not only thermodynamics or physical restrictions imposed by surface stabilizing molecules. We have prepared several examples of anisotropic noble metal nanocrystals obtained by different methods and produced a careful analysis of their structure. Primarily, the important role of twinning in determining the habit of the final morphology will be discussed.
9:00 PM - Q20.2
Mechanical Properties of Carbon Nanotubes / Polyvinyl Alcohol Composites Produced by Electrospinning.
David Blond 1 , Leslie Carpenter 1 , Joe Mc Cauley 1 , Umar Khan 1 , Werner Blau 1 , Jonathan Coleman 1
1 school of physics, TCD, Dublin Ireland
Show AbstractCarbon nanotubes (CNTs) have outstanding mechanical properties, making them an excellent candidate for use as fillers to reinforce polymer matrix. However, this improvement is achievable only with a good dispersion of CNTs within the polymer. Previous reports have shown that Polyvinyl Alcohol (PVA) is a suitable matrix to reach this goal [1, 2]. Several PVA / CNTs composites have been realised by solution processing such as drop casting (films) and coagulation spinning methods (fibers). Both methods have shown a dramatic increase in the mechanical properties of the system as a result of the addition of low volume fractions of nanotubes [3, 4, 5]. Recently, an alternative method called electrospinning has been developed to form composite based fibers. This technique involves electrostatically driving a jet of polymer solution out of a nozzle onto a metallic counter-electrode [6]. We used this method to produce PVA/CNTs electrospun nanofibers. Mechanical properties of both electrospun composite fibers and drop casted composite films were measured using tensile testing and dynamic mechanical thermal analysis (DMTA). Morphological studies were carried out using Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Atomic Force Microscopy (AFM) in order to examine both the CNT dispersion and the microstructure of the composites. Thermal analyses, such as Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA), were also performed. [1] Shaffer MSP, Windle AH. Fabrication and Characterization of Carbon Nanotube/Poly(vinyl alcohol) Composites. Advanced Materials. 1999;11(11):937-41.[2] Cadek M, Coleman JN, Ryan KP, Nicolosi V, Bister G, Fonseca A, et al. Reinforcement of Polymers with Carbon Nanotubes: The Role of Nanotube Surface Area. Nano Lett. 2004;4(2):353-6.[3] Coleman JN, Cadek M, Blake R, Nicolosi V, Ryan KP, Belton C, et al. High Performance Nanotube-Reinforced Plastics: Understanding the Mechanism of Strength Increase. Advanced Functional Materials. 2004;14(8):791-8.[4] Dalton AB, Collins S, Munoz E, Razal JM, Ebron VH, Ferraris JP, et al. Super-tough carbon-nanotube fibres - These extraordinary composite fibres can be woven into electronic textiles. Nature. 2003;423(6941):703-.[5] Miaudet P, Badaire S, Maugey M, Derre A, Pichot V, Launois P, et al. Hot drawing of single and multiwall nanotube fibers. Submitted to Nano Letters. 2005.[6] Formhals A, inventor Electrical Spinning of Fibers fromSolutions. United States. 1934.
9:00 PM - Q20.20
Structure and Nano-mechanics of CNT/a-SiC Composites via Molecular Dynamics Simulations.
Maxim Makeev 1 , Deepak Srivastava 1 , Madhu Menon 2
1 , NASA Ames Research Center, Moffett Field, California, United States, 2 Department of Physics and Astronomy and Center for Computational Sciences, University of Kentucky, Lexington, Kentucky, United States
Show Abstract9:00 PM - Q20.21
Use of Electrochemical Deposition and Hyperthermal Proton Bombardment to Fabricate Multi-walled Carbon Nanotube Adherent Coatings with Improved Cohesive Strength.
Ching Yeung Choi 1 2 , Kai Wai Wong 1 2 , Zhi Zheng 3 , Zao Liang Du 4 , Ru Xu Du 1 , Leo Lau 5
1 , Institute of Precision Engineering, The Chinese University of Hong Kong, Hong Kong Hong Kong, 2 Physics, The Chinese University of Hong Kong, Hong Kong Hong Kong, 3 , Institute of Surface Micro and Nano Materials, Xuchang Uiversity, Xuchang China, 4 , Laboratory for Special Functional Materials, Henan Uiversity, Kaifeng China, 5 , Surface Science Western, University of Western Ontario, London, Ontario, Canada
Show AbstractCarbon nanotube (CNT) has been under extensive study on their electrical and mechanical properties since 1990s. A lot of innovative and novel applications such as CNT-based electronics, solid lubricant and lab-on-a-chip biomedical sensor are being developed based on the extraordinary and unique properties of CNT. For most of these applications, a fabrication technique for CNT coatings with high stability, strong adhesion and cohesive strength is of critical importance. In the present study, a two-step synthesis consisting of (i) electrochemical deposition, and (ii) hyperthermal proton bombardment, was developed for deposition of multi-walled CNT (MWCNT) coatings with highly improved stability, adhesion and intrinsic strength.MWCNTs were oxidized by an acid mixture to give functionalized MWCNTs (f-MWCNTs) with surface carboxylic acid groups. F-MWCNTs were then coated onto metal substrates by electrochemical deposition under a low electric field (< 2 V/cm). It was observed that the electrochemical reactions between f-MWCNTs and substrate have significantly improved the adhesive strength of the coating through the formation of chemical bonds between the carboxylic acid groups from f-MWCNTs and metal from the substrate. Upon subsequent hyperthermal proton bombardment, the cohesive strength of the f-MWCNT coating was found greatly increased due to the formation of inter-tube cross-linkages induced.The stability, frictional characteristics, adhesive and cohesive strength of f-MWCNTs films before and after bombardment were studied by local force spectroscopy (LFS), pin-on-disk test and also specially designed solubility tests. When compared with MWCNT coatings prepared by common electrophoretic deposition, the coating fabricated by the reported two-step synthesis exhibits a much lower adhesive force to the cantilever used in LFS, implying a significantly smaller attractive interaction between the coating and the cantilever. Also, the coating shows better frictional characteristics with stronger mechanical strength towards rubbing against a constant load during pin-on-disk tests. Furthermore, the coating possesses higher film durability and stability as shown by its enhanced resistance towards ultrasonic rinsing and flow stress under both aqueous and organic solvents. These improvements will be explained in terms of the electrochemical reactions occurred during deposition and the cross-linkages formed among f-MWCNTs upon hyperthermal proton bombardment. The effects of (i) degree of functionalization, (ii) nature of functionalization, (iii) proton energy, and (iv) proton dosage will be discussed. The experimental results, as well as the underlying science and technology, will also be reported in details.
9:00 PM - Q20.22
Electromechanical Sensors Based on Ultra Long Free Standing Aligned Carbon Nanotubes.
Victor Pushparaj 1 , Lijie Ci 1 , Jonghwan Suhr 1 , Omkaram Nalamasu 1 , Ajayan Pulickel 1
1 Materials Science and Engg., Rensselaer Polytechnic Institute, troy, New York, United States
Show Abstract9:00 PM - Q20.23
In-situ Mechanical Probing of Nanostructures with AFM-TEM System.
Alexandra Nafari 1 3 , Oleg Lourie 2 , David Karlen 3 1 , Krister Svensson 3 , Peter Enoksson 3
1 , Nanofactory Instruments, Gothenburg Sweden, 3 , Chalmers University of Technology, Gothenburg Sweden, 2 , Gatan Inc., Pleasanton, California, United States
Show Abstract9:00 PM - Q20.24
Conductive MWNT/Poly(Vinyl Acetate) Composite Nanofibers by Electrospinning.
Guan Wang 1 , Vladimir Samuilov 1 , Ja-Seung Koo 1 , Zhongkui Tan 2 , Xueqing Liu 2 , Michael Dudley 1
1 Materials Science Dept., Stony Brook University, Stony Brook, New York, United States, 2 Department of Physics and Astronomy, Stony Brook University, Stony Brook , New York, United States
Show Abstract9:00 PM - Q20.25
Atomic Force and Optical Microscopy Characterization of the Deformation of Individual Carbon Nanotubes and Nanofibers.
Terry Bigioni 1 , Alan Cassell 1 , Joseph Leung 1 , Cattien Nguyen 1 , Brett Cruden 1
1 Center for Nanotechnology, NASA Ames Research Center, Moffett Field, California, United States
Show Abstract9:00 PM - Q20.26
Fast Growth of Long, Vertical Carbon Nanotube Arrays for Spinning Strong Fibers.
Qingwen Li 1 , XieFei Zhang 1 , Raymond DePaula 1 , Lianxi Zheng 1 , Yonghao Zhao 1 , Liliana Stan 1 , Terry Holesinger 1 , Paul Arendt 1 , Dean Peterson 1 , Yuntian Zhu 1
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show Abstract9:00 PM - Q20.27
Elastic Properties of Normal and Binormal Helical Nanowires.
Alexandre da Fonseca 1 , Coraci Malta 1 , Douglas Galvão 2
1 , Instituto de Física, Universidade de Sao Paulo, Sao Paulo, Sao Paulo, Brazil, 2 , Instituto de Física 'Gleb Wataghin', Universidade Estadual de Campinas, Campinas, Sao Paulo, Brazil
Show Abstract9:00 PM - Q20.28
Impact of Buckling and Adhesion on the Mechanical Response of Vertically Aligned Carbon Nanotube Structures.
David Bahr 1 , C. McNee 1 , A. Zbib 1 , C. Richards 1 , S. Mesarovic 1 , R. Richards 1 , D. McClain 2 , J. Jiao 2 , K. Sinnathamby 3 , H. Ma 3 , C. Yip 3
1 Mechanical and Materials Engineering, Washington State University, Pullman, Washington, United States, 2 Department of Physics, Portland State University, Portland, Oregon, United States, 3 Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
Show Abstract9:00 PM - Q20.29
Polymer Coated Carbon Nanotubes Probes for Scanning Electrochemical Microscopy.
Amol Patil 1 , A. Beker 1 , G. Coslovich 1 , T. Oosterkamp 1
1 LION, Leiden University, Leiden Netherlands
Show Abstract9:00 PM - Q20.3
Effect of Carboxy-Functionalized Multiwall Nanotubes (MWNT-COOH) on the Crystallization and Chain Conformations of Poly(Ethylene Terephthalate) PET in PET-MWNT Nanocomposites.
Vasilis Gregoriou 1 , Spiros Tzavalas 1 , Vasilis Drakonakis 1 , Dionysis Mouzakis 2 , Georgia Kandilioti 1 , Dieter Fischer 3
1 , Foundation for Research and Technology - Hellas, Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), Patras, Achaia, Greece, 2 Department of Materials Science, University of Patras, Patras, Achaia, Greece, 3 , Leibniz Institute of Polymer Research (IPF), Dresden Germany
Show Abstract9:00 PM - Q20.31
Sensor and Controller Design of Microcantilever Arrays Using Carbon Nanotube Tip for Electrochemical Sensing, Imaging and Manipulation.
Eunjeong Lee 1
1 , KAIST, Daejeon Korea (the Republic of)
Show Abstract9:00 PM - Q20.32
Scaling, Design and Self-assembly of Nanotube-based Electromechanical Devices.
Roland Lefèvre 1 , Erik Dujardin 2 , Marcelo Goffman 1 , Vincent Derycke 1 , Patrice Hesto 3 , Jean-Philippe Bourgoin 1
1 SPEC, CEA Saclay, Gif sur Yvette France, 2 Nanoscience Group, CEMES CNRS, Toulouse France, 3 IEF, Université de Paris Sud - Orsay, Orsay France
Show AbstractCarbon nanotubes are ideal candidates for the bottom-up fabrication of nano-electro-mechanical systems (NEMS) due to their well-characterized chemical and physical structures, and their exceptional mechanical and electrical properties. In particular, their high conductivity allows for designing simple sensing and actuation systems based on the direct electrostatic coupling with metallic gates. Their exceptional stiffness, low mass, and dimensions ensure future operating frequencies in the GHz range making them suitable for a number of applications.But understanding the subtle interplay between the physical, geometrical and electrical parameters of the system is crucial to accurately design nanotube NEMS [1,2]. We present a combined theoretical and experimental (AFM based) study [3] which allows the quantitative determination of the electrostatic deflection efficiency of suspended MWNTs as well as their Young's modulus. We show in particular that the relation between the maximal deflection of a suspended nanotube and the applied actuation voltage, can be scaled into a universal curve that only depends on the geometrical parameters of the device and on the Young's modulus of the nanotube. Such a scaling law provides a generic tool for properly designing actual devices. The second step is to develop fabrication techniques that allow a very precise control over the geometrical parameters, in particular: the nanotubes localization and the separation between the nanotubes and the actuating electrodes. As an example, we present two-terminal nanotube electromechanical switches based on singly clamped, self-assembled and suspended MWNTs. The self-assembly techniques relies on the chemical modification of a patterned substrate using a molecular mono-layer of amino-silane [4,5]. This local functionnalization guides the selective deposition of MWNTs from an organic solvent. The presented switches [5] show extremely sharp electrical transitions between an Off-state (no contact between the tube and the actuating electrode) and an On-state (tube in contact) with the current changing by several orders of magnitude within a 100 mV change of the actuating electrode bias above a threshold corresponding to the mechanical pull-in voltage.
[1] Duquesnes et al., Nanotechnology 13, 120 (2002).[2] Kinaret et al., Appl. Phys. Lett. 82, 1287 (2003) and J. of Appl. Phys. 96, 629 (2004).[3] Lefèvre et al, Phys. Rev. Lett. 95, 185504 (2005).[4] Choi et al, Surf. Sci. 462, 195 (2000); E. Valentin et al, Microelec. Eng. 61, 491 (2002); Auvray et al, Nano Lett. 5, 451 (2005).[5] Dujardin et al, Appl. Phys. Lett. 87, 193107 (2005).
9:00 PM - Q20.33
Vertically Oriented Carbon Nanofiber Based Nanoelectromechanical Switch.
Brett Cruden 1 , Alan Cassell 1 , Dmitry Kozak 2 , Joel Kubby 2
1 Center for Nanotechnology, NASA Ames UARC, Moffett Field, California, United States, 2 Electrical Engineering, University of California, Santa Cruz, Santa Cruz, California, United States
Show Abstract9:00 PM - Q20.34
Chemically Modified Multiwalled Carbon Nanotubes as an Additive for Supercapacitors.
Yong-Jung Kim 1 , Yusuke Abe 2 , Takashi Yanagiura 2 , Masaaki Kitani 2 , Tsuyoshi Kodama 2 , Keita Higuchi 2 , Morinobu Endo 1 2
1 , Institute of Carbon Science & Technology, Shinshu University, Nagano, Nagano, Japan, 2 Electric and electronic engineering, Shinshu University, Nagano, Nagano, Japan
Show AbstractHere we demonstrate that the incorporation of chemically modified multi-walled carbon nanotubes (MWNTs), as an additive material to enhance the electrical conductivity, into the electrode gives rise to a highly improved rate capability of a super-capacitor. The preferential attack of potassium hydroxide on less disordered carbon results in the formation of high-performance MWNTs with increased surface area, electrical conductivity and sustained long tube morphology, simultaneously. The enhancing effect by the novel additives was demonstrated using phenolic-resin based activated carbon electrode that is most widely used in supercapacitor industries as electrode active material. Carbon black was confirmed as a standard for the comparison. Experimental results demonstrate the superiority of MWNT activated using KOH as a conducting additive, which improve the capacitance and conductivity, and are consistent with those of all structural analyses. It is envisaged that newly developed functional MWNTs will be utilized in various electrochemical systems, where high current is critically required.
9:00 PM - Q20.35
Bilayer Organic/Inorganic Gate Dielectrics for High Performance, Low-Voltage Single Walled Carbon Nanotube Thin-Film Transistors, Complementary Logic Gates and p-n Diodes on Plastic Substrates.
Qing Cao 1 3 4 , John Rogers 2 3 4
1 Chemistry, University of Illinois at Urbana Champaign, Urbana, Illinois, United States, 3 Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 4 Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractHigh capacitance bilayer dielectrics based on atomic-layer-deposited HfO2 and spin-cast epoxy are used with networks of single-walled carbon nanotubes (SWNTs) to enable low-voltage, hysteresis-free and high performance thin film transistors (TFTs) on silicon and flexible plastic substrates. These HfO2/epoxy dielectrics exhibit excellent properties including mechanical flexibility, large capacitance (up to ~330 nF/cm2) and low leakage current (~10-8 A/cm2); their low temperature (~150C) deposition makes them compatible with a range of plastic substrates. The experimental and theoretical results illuminate attractive properties of these dielectrics and their behavior in TFTs, including fringing field contributions to gate capacitance, hysteresis and other properties. Their compatibility with polymers used for charge transfer doping of SWNTs is also demonstrated through the fabrication of n-channel SWNT TFTs, low voltage p-n diodes and complementary logic gates.
9:00 PM - Q20.36
Carbon Nanotube Networks as Gas Sensors.
Edgar Munoz 1 , Isabel Sayago 2 , Eva Terrado 1 , Manuel Aleixandre 2 , Maria del Carmen Horrillo 2 , Maria Jesus Fernandez 2 , Esperanza Lafuente 1 , Wolfgang Maser 1 , Ana Benito 1 , Javier Gutiérrez 2 , Maria Teresa Martinez 1
1 , Instituto de Carboquimica-CSIC, Zaragoza Spain, 2 Laboratorio de Sensores, IFA-CSIC, Madrid Spain
Show Abstract9:00 PM - Q20.38
Thermal Conductivity of Ultrathin Carbon Nanotubes with an X-shaped Junction.
Fanyan Meng 1 2 , Shigenobu Ogata 1 , Dongsheng Xu 2 , Sanqiang Shi 3
1 Mechanical Engineering, Graduate School of Osaka Univeristy, Osaka Japan, 2 , Institute of Metal Research, Chinese Academy of Sciences, Shenyang, Liaoning, China, 3 Mechanical Engineering, Hong Kong Polytechnic University, Hong Kong China
Show AbstractCarbon nanotube junctions are excellent candidates for nanoscale multiterminal electronic devices due to their high thermal conductivity, superior electrical and mechanical properties, as well as their inherent nanosize[1]. The thermal conductivity of materials at nanoscale is becoming an increasingly important issue, since significant amount of heat may need to be dissipated to prevent the structural damage. Four kinds of symmetric X-shaped junctions, with all atoms remained sp2 hybridized, can be formed between two crossed ultrathin carbon nanotubes[2]. The thermal conductivity of an ultrathin carbon nanotube with and without an X-shaped junction has been investigated using a molecular dynamics approach with the reactive empirical bond order potential. Carbon nanotube was placed in contact with two reservoirs with different temperature, and the thermal conductivity was related to the heat flowing with temperature gradient based on the Fourier’s law when the system reached the steady state. It was found that thermal conductivity of the tube with a junction was 35~55% less than that of a corresponding straight tube depending on the temperature and geometry. Topological defects in the form of enneagons, octagons and heptagons around the junctions resulted in a discontinuity in the temperature profile. The geometries of the junctions and the distance between the crossed tubes influenced the thermal conductivity of the tube.1.M. Terrones, F. Banhart, N. Grobert, J. C. Charlier, H. Terrones, and P. M. Ajayan, Phys. Rev. Lett., 89, 075505 (2002); A. N. Andriotis, M. Menon, D. Srivastava, and L. Chernozatonskii, Phys. Rev. Lett., 87, 066802 (2001); S. Berber, Y. K. Kwon, and D. Tománek, Phys. Rev. Lett., 84, 4613 (2000)2.F. Y. Meng, S. Q. Shi, D. S. Xu, and R. Yang, Phys. Rev. B, 70, 125418 (2004); F. Y. Meng, S. Q. Shi, D. S. Xu, and C. T. Chan, Modelling and Simulation in Materials Science and Engineering, 14, S1 (2006)
9:00 PM - Q20.39
Measuring the Temperature of Electrically Heated Carbon Nanotubes by Raman Spectroscopy
Hootan Farhat 1 , Hyungbin Son 2 , Jing Kong 2
1 Materials Science and Engineering, MIT, Cambridge, Massachusetts, United States, 2 Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts, United States
Show AbstractHeat dissipation plays an important role in the performance of carbon nanotube electronic devices. Recent experiments on suspended nanotubes suggest that there is significant electrical heating in devices that lack heat sinking from the substrate [1]. In this work, we have measured the temperature of suspended/non-suspended nanotube devices as a function of applied electric field, by performing simultaneous Raman spectroscopy and electrical transport measurements. The nanotube temperature is determined directly from the shift in the G-band Raman peak. This result provides insight on electron phonon scattering in carbon nanotubes as well as on electrically induced thermal breakdown of nanotube devices.[1] E. Pop et al., Physical Review Letters 95, 155505 (2005)
9:00 PM - Q20.4
Freely Suspended Carbon Nanotube Monolayer Array Encapsulated into Polyelectrolyte Multilayer Films.
Hyunhyub Ko 1 2 , Chaoyang Jiang 1 2 , Vladimir Tsukruk 1 2
1 Materials Science and Engineering, Iowa State University, Ames, Iowa, United States, 2 Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractWe demonstrate the successful fabrication of carbon nanotube microscopic arrays encapsulated into freely suspended polyelectrolyte membranes by using Layer-by-layer (LbL) assembly and sacrificial polymer patterning. Well-defined polymer micropatterns have been fabricated by microcontact printing or capillary transfer lithography and used as a protective template for guided LbL assembly of nanoparticle arrays. Removal of the protective polymer layer after the first step exposed electrostatically active surface areas, thus, allowing further deposition of LbL multilayers resulting in carbon nanotube arrays sandwiched between LbL films. These freely suspended carbon nanotube arrays represent excellent candidates for multifunctional membrane sensors requiring high electrical conductivity and extreme robustness.
9:00 PM - Q20.40
Thermal and Electrical Degradation of Carbon Nanotubes.
Yan Liu 1 , Feng Jin 1 , Christopher Day 1 , Scott Little 1
1 Physics and Astronomy, Ball State University, Muncie, Indiana, United States
Show AbstractDegradation of carbon nanotubes (CNTs) significantly affects CNT’s electron emission capability, and is important to CNTs applications as electron emitter. In this study, vertically aligned CNTs were grown on tungsten substrates via plasma enhanced chemical vapor deposition (PE-CVD). Two causes of CNT degradation, thermal and electrical degradations were identified and studied by examining the surface morphology changes of the CNT emitters using scanning electron microscopy (SEM) and correlating to their field emission properties. It was found that heating the sample to a temperature as high as 1500 °C led to thermal degradations. The origins of the thermal degradation were at the joints of CNTs and tungsten substrate, which were not strong enough to withstand the high temperature treatment, causing the collapse of the CNTs at the interface and consequently destroying the alignment of CNTs. The electrical degradation occurred at high electric field and high emission current. SEM images revealed that the CNT tips were damaged by the large emission current density (up to 23.4 mA/cm2) at high field. The degradation of electron emission properties of the emitters was due to the deformation and collapse of the CNT tips.
9:00 PM - Q20.41
Heat Transfer from Carbon Nanotube-based Extended Surfaces.
John Shelton 1 , Frank Pyrtle 1
1 Mechanical Engineering, University of South Florida, Tampa, Florida, United States
Show Abstract9:00 PM - Q20.42
Thermal Imaging of Nanoscale Heater Wires on MEMS Substrates.
Kamal Baloch 1 , Todd Brintlinger 2 4 , Yi Qi 2 4 , William Cullen 3 , John Cumings 2 4
1 Chemical Physics, University of Maryland , College Park, Maryland, United States, 2 Material Science and Engineering, University of Maryland , College Park, Maryland, United States, 4 Center for Superconductivity Research, University of Maryland, College Park, Maryland, United States, 3 Physics, University of Maryland , College Park, Maryland, United States
Show AbstractWe present real-time, in situ, high-resolution thermal imaging of local resistive heating on MEMS substrates. Using a transmission electron microscope (TEM), the liquid/solid transition in small, 20-200nm diameter indium islands can be imaged over a field-of-view ofseveral microns. These dots are present in a roughly uniform,discontinuous film on the back-side of a silicon nitride membrane. Joule heating in a long, thin metal wire on the front-side of the membrane provides local thermal gradients which melt/freeze the individual indium islands on the back. The images can then be mapped and recorded at video rates. Transitions in individual islands occurwithin 1-3 video frames (33 msec each) and exhibit a hysteresis in temperature. This hysteresis is reproducible upon thermal cycling of individual islands and does not depend cycling speed. We present evidence of these phenomena along with thermal modeling to corroborateimaged thermal behavior. This technique should be generally useful for local thermal imaging of nanowire and nanotube systems, and results for a carbon nanotube spanning two electrodes will be shown.
9:00 PM - Q20.43
Modified Blackbody Emission from Carbon Nanotube Devices.
Andrew Walsh 1 , Ben Schlatka 2 , Mitch Meinhold 2 , Thomas Rueckes 2 , Michael Linehan 2 , A. Vamivakas 3 , Yan Yin 1 , M. Unlu 3 1 , Bennett Goldberg 1 3 , Anna Swan 3
1 Physics, Boston University, Boston, Massachusetts, United States, 2 , Nantero, Inc., Woburn, Massachusetts, United States, 3 Electrical And Computer Engineering, Boston University, Boston, Massachusetts, United States
Show AbstractWe measure the spectrum of emission from a carbon nanotube network contacted by metal electrodes. Visible and near infrared (NIR) emission from carbon nanotubes under applied voltage is well modeled by a blackbody curve modified by the electronic density of states. The spectral emission of any material in thermal equilibrium includes an emissivity prefactor that modifies the blackbody response. While generally taken as a constant or as a slowly varying function of wavelength, the emissivity should properly reflect the dielectric function of the material and is therefore a complex function of the electronic system, phonons, plasmons, etc. In the visible and NIR region of the spectrum, the emissivity is dominated by the electronic structure of the carbon nanotubes. The one-dimensional nature of the nanotubes leads to sharp excitonic peaks in the density of states which are reflected in the blackbody spectrum. Specifically, our measurements of nanotube emission under applied bias are well modeled by electronic transitions within a blackbody envelope function.
9:00 PM - Q20.44
Molecular Dynamics Simulations of Carbon Nanotube/Silicon Substrate Interfacial Thermal Conductance.
Jiankuai Diao 2 1 , Deepak Srivastava 2 1
2 , University of California, , Santa Cruz, California, United States, 1 , NASA Ames Center for Nanotechnology, Moffett Field, California, United States
Show Abstract9:00 PM - Q20.45
Anharmonic Effects in Carbon Nanotubes, Graphene and Graphite: Thermal Expansion and Phonon Lifetimes.
Nicola Bonini 1 , Nicolas Mounet 1 , Michele Lazzeri 2 , Francesco Mauri 2 , Nicola Marzari 1
1 Department of Materials Science and Engineering, MIT, Cambridge, Massachusetts, United States, 2 , Institut de Minéralogie et Physique des Milieux Condensés, Paris France
Show Abstract9:00 PM - Q20.46
High Concentration Carbon Nanotube Oil Solution for Thermal Applications.
Yoichi Taira 1 , Kuniaki Sueoka 1
1 Tokyo Research Lab, IBM, Yamato Japan
Show AbstractThe cooling solution of future high power VLSI chips requires heat conducting materials in a flexible form having very high conductivity. Oil containing silica fillers or metal particle fillers have been used to enhance the thermal conductivity of thel grease. Although there are many discussions on the use of carbon nanotubes (CNTs) as the fillers in the oil to enhance the thermal conductivity, it has not been straightforward to take advantage of the high thermal conductivity of CNTs to realize the super performance thermal grease. Assuming the thermal conductivity of single wall CNT (SWCNT) 1900 W/mK, high concentration CNT solution in liquid more than 10% volume content can give such a super thermal grease. However, simple increase of concentration of CNTs leads to a non-fluidic hard mixture due to the entanglement of CNT wires, which makes the grease not useful as the thermal interface materials. We could show that the entanglement is avoided by using appropriate surfactant and the high pressure mixture process between fluid and CNTs as well as the length control of CNTs. Thus, we could achieve CNT grease up to 20% volume filling factor. One interesting aspect of using CNTs is the linear shape of CNTs. Use of the linear shaped CNT is also effective to achieve better thermal conductivity, compared to the use of spherical fillers in the ordinary thermal greases. Thermal performance and the details of the mixture process will be reported.
9:00 PM - Q20.47
Carbon Evaporation from Carbon Nanotube Field Emitters Studied by Conductivity Change of CNT Anode.
Alexander Kuznetsov 1 , Ren Chong Hu 1 , Mei Zhang 1 , Sergey Lee 1 , Ray Baughman 1 , Anvar Zakhidov 1
1 NanoTech Institute, University of Texas at Dallas, Dallas, Texas, United States
Show AbstractThe study of degradation of carbon nanotube (CNT) electron field emitters under high current conditions allowed to reveal interesting details of carbon evaporation from the CNT cathodes. Single-wall and multi-wall CNT papers were investigated as electron field emissive cathodes. Due to high field emission currents going through small number of protruded nanotubes, only those nanotubes overheat and melt at the ends, evaporating C atoms and small clusters. Evaporated carbon atoms deposit on the anode forming spherical and elliptical patterns, which are similar in shape to the patterns, induced on phosphorescent screens by field emitted electrons. To clarify the details of carbon deposition we used transparent CNT thin films and CNT aerogel sheets [1] as anodes and found that deposited carbon layers significantly decrease the resistance of CNT films with only a small decrease in transparency. Thus this method allows to decrease the sheet resistance of T-CNT from 700 ohm/sq to 100 ohm/sq level, required for many optoelectronic applications. The structure of deposited C and origin of deposition patterns are analyzed and discussed in terms of correlated ionic and electronic flows. [1] M. Zhang, S. Fang, A. Zakhidov, S. B. Lee, A. Aliev, R.H. Baughman, Science, 309,(2005) 1215
9:00 PM - Q20.49
Influence of Electrostatic Field on Storage of Hydrogen in Carbon Nanotubes.
Soumik Banerjee 1 , Sohail Murad 2 , Ishwar Puri 1
1 Engineering Science and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States, 2 Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois, United States
Show AbstractA benchmark has been set by the US Department of Energy (DOE) for hydrogen storage, which is 6.5 weight percent of the species in a storing material and a volumetric density of 62 kg H2/m3. Development of suitable storage and delivery systems, capable of meeting this target, is therefore necessary to facilitate the use of hydrogen as a fuel. Considerable research in recent years has been focused on finding a suitable material that can store adequate amount of hydrogen. Allotropes of carbon are known to adsorb large quantities of hydrogen due to the strong intermolecular attractive forces between hydrogen and carbon. This, in conjunction with exceptional capillarity and high surface area, leads to hydrogen adsorption in carbon nanotubes (CNTs). However, experimental results reported by researchers for the maximum hydrogen storage in CNTs at room temperature show wide disparity. Theoretical calculations have shown that the storage capacity at normal temperature and pressure is limited and does not meet the target set by the DOE. Our research focuses on improving the potential for hydrogen storage in CNTs, via increased understanding at the fundamental molecular level. We investigate such behavior using molecular dynamic simulations and suggest possible changes in the structure and conditions of CNTs that might enhance the storage capacity. The hydrogen transport characteristics inside and on the surface of a nanotube in the presence of an electrostatic field and/or metal ions have been simulated using molecular dynamics method. It is found that the presence of an electrostatic field and encapsulation of metal ions inside the nanotubes are two vital factors that modify the adsorption characteristics. Both armchair and zigzag CNTs have been simulated in order to investigate the effect of the structure of CNT on storage performance. Future directions to improve storage characteristics have been suggested based on the results obtained from these molecular dynamics investigations.
9:00 PM - Q20.5
Multiwalled Carbon Nanotube-PDMS Composite Systems for Electronic Applications.
Melissa Harrison 1 , Stephanie Getty 2 , Patrick Roman 2 , Louis Barbier 2
1 Physics, Fisk University, New Orleans, Louisiana, United States, 2 , NASA Goddard Space Flight Center, Greenbelt, Maryland, United States
Show AbstractVertically aligned multiwalled carbon nanotubes (MWCNTs) have been integrated into a poly(dimethysiloxane) (PDMS) matrix. Once cured, the MWCNT-PDMS system was easily separated from the silicon substrate along with a remnant catalyst film. The metal catalyst residue is a contaminant to the composite and techniques for removal will be discussed. Using scanning electron microscopy for characterization, imaging has shown that the PDMS elastomer permeates the nanotube network, encasing the nanotubes. PDMS provides potent support and serves as a conformal substrate which has been reported to adhere to a variety of surfaces [ref]. The MWCNT-PDMS system can be easily deformed without surpassing elastic deformation or disorienting the nanotube network. Results from a field emission test and anticipated applications, such as an electron gun in miniaturized analytical instruments, for space and planetary science will be discussed. Further investigation is expected to demonstrate the MWCNT-PDMS system’s ability to maintain characteristics that make the composite suitable where electrically and mechanically stable systems are needed.
9:00 PM - Q20.50
Effects of Post Treatment and Duty Factor on the Field Emission Stability of Carbon Nanotubes.
Sigen Wang 1 , Sha Chang 1
1 Division of Physics & Computing, Medical School, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
Show AbstractCarbon nanotubes have been investigated as field emission sources for a number of applications including x-ray source, microwave power amplifier, field emission displays and nanolithography system. These applications require that nanotubes provide a stable field emission with a required emission current. In this study, the carbon nanotubes were grown using a microwave plasma enhanced chemical vapor deposition technique and subsequently subjected to a hydrogen plasma treatment. The emission stability of the carbon nanotubes was examined. It was found that the plasma treated sample has a higher emission stability. Besides, at a high emission current (>1 mA), the fluctuation in emission current becomes larger at high duty factor (duty factor is defined as the ratio of the electron field emission time to the total cycle time). The possible mechanism has been discussed in terms of the characterization results.
9:00 PM - Q20.51
Temperature- and Field-dependent Electron Emission from Carbon Nanotube Emitters.
Scott Little 1 , Feng Jin 1 , Yan Liu 1
1 Physics and Astronomy, Ball State University, Muncie, Indiana, United States
Show AbstractIn the past, field emission has been the primary emission studied from carbon nanotubes (CNTs) and relatively few have studied thermionic emission from CNTs. We have preformed detailed measurements of temperature- and field-dependent electron emission of CNTs and have improved oxide coated CNT emitters over a wide range of fields and temperatures. In this presentation, we will focus particularly on the temperature and field region that is neither field nor thermionic emission—which cannot be described by either the Fowler-Nordheim theory (field emission) or the Richardson theory (thermionic emission). Detailed experimental results of electron emission from CNTs at different temperatures and field strengths will be presented. The experimental data will be compared to the numerical simulation which is based on the model developed by Murphy and Good (1). The simulation program is a self-consistent setup based on initial conditions (i.e. work function, temperature, electric field strength, field enhancement factor) such that physical quantities such as the current density and work function can be predicted. Empirical data from the experiment can be assimilated into the input parameters of the program until the output is self-consistent (i.e. input work function equals the output work function with error limits). Details of the simulation program will be described.
1. Murphy, E. L. Good, R. H. "Thermionic emission, field emission, and the transition region." Physical Review 102(1956): 1464-1473.
9:00 PM - Q20.52
Fabrication And Modeling Of Gated Field-emission Devices Using Carbon Nanotubes on Si Substrates.
Javad Koohsorkhi 1 , Yaser Abdi 1 , Shams Mohajerzadeh 1 , Michael Robertson 2
1 Electrical and Computer Eng., university of Tehran, Tehran, Tehran, Iran (the Islamic Republic of), 2 Physics, Acadia University, Wolfville, Nova Scotia, Canada
Show Abstract9:00 PM - Q20.53
Optoelectronic Properties of Thin Films of SWNTs From Different Commercial Sources.
Husnu Unalan 1 , Giovanni Fanchini 1 , Steve Miller 1 , Manish Chhowalla 1
1 Materials Science and Engineering, Rutgers University, Piscataway, New Jersey, United States
Show Abstract9:00 PM - Q20.54
Photoluminescent Characteristics of Ni-catalyzed GaN Nanowires.
Jinkyoung Yoo 1 , Young Joon Hong 1 , Sung Jin An 1 , Gyu-Chul Yi 1 , Bonghwan Chon 2 , Taiha Joo 2
1 Mateirals Sci. & Eng., POSTECH, Pohang, Gyeongbuk, Korea (the Republic of), 2 Chemistry, POSTECH, Pohang, Gyeongbuk, Korea (the Republic of)
Show Abstract9:00 PM - Q20.55
Preparation and Photocatalytic Property of ZnO/MWCNTs Composites.
Ying Yu 2 1
2 , HuaZhong Normal University, Wuhan China, 1 , Boston College, Chestnut Hill, Massachusetts, United States
Show Abstract9:00 PM - Q20.56
Optical Properties of Si Nanowire Films.
Loucas Tsakalakos 1 , Joleyn Balch 1 , Jody Fronheiser 1 , Matthew Pietrzykowski 1 , Peter Codella 1 , Jim Rand 2 , Oleg Sulima 2 , Anil Kumar 3
1 , General Electric - Global Research Center, Niskayuna, New York, United States, 2 , GE Energy, Newark, Delaware, United States, 3 , General Electric - John F. Welch Technology Center, Bangalore India
Show AbstractOne dimensional semiconducting nanowires have generated intense scientific and technological interest in the past few years. While there are several techniques known in the literature for synthesizing these nanostructures, they are typically grown on a substrate using chemical vapor deposition (CVD) in which a nanowire “film” composed of randomly oriented nanowires is produced. It is also possible to grow aligned nanowire arrays on suitable substrates and under certain growth conditions. One fundamental aspect of such nanowire assemblies that has generally been overlooked both theoretically and experimentally is how light interacts with them. The typical diameters of nanowires, ca. 3-150 nm, are below the wavelength of light used in typical experimental optical measurements (300 nm -25 microns), whereas their lengths may range from 0.5-20 microns. This “structural” anisotropy, coupled with crystallographic anisotropy, may lead to unique optical properties of such films. Here we examine the impact of silicon nanowire assembly structure, including nanowire diameter, pitch, length, and orientation on standard optical properties such as reflectance, absorption, and transmission. This is studied via a combination of modeling work, performed using both conventional free-space optical modeling and finite-difference time domain (FDTD) schemes, and the use of total reflectance and transmission measurements. Initial results show that the total reflectance of aligned nanowire arrays (without a catalyst) is lower than control Si wafers over all wavelengths (300-1500 nm) and is also lower than randomly oriented nanowire films between 300 and ~1060 nm. The reflectance of the aligned arrays varies from ~1.5% at 300 nm to ~9% at 1000 nm. We also find that the diameter of the nanowires impacts the reflectance, with smaller diameter nanowires providing less reflectance. Furthermore, the total absorption of light in nanowire arrays on glass substrates is higher compared to solid thin films of equivalent thickness. Nanowires formed by an etch process show high residual absorption below the bandgap (~ 20%), implying defect states contribute significantly to the enhanced absorption, whereas CVD-grown Si nanowires, which also show high residual below badngap absorption, are believed to show a strong interaction between the nanowires and the metal nanoparticles embedded in the film. The described effects will be correlated with results of the aforementioned modeling studies.
9:00 PM - Q20.57
Transparent Multi-wall Carbon Nanotubes Laminated as Top Electrode in Organic Solar Cells.
Kanzan Inoue 1 2 , Kamil Mielczarek 1 2 , Brian Wang 1 2 , Dean Hsu 1 2 , Sergey Lee 1 , Mei Zhang 1 , Shaoli Fang 1 , Ray Baughman 1 3
1 NanoTech Institute, Universty of Texas at Dallas, Richardson, Texas, United States, 2 Physics Departement, Universty of Texas at Dallas, Richardson, Texas, United States, 3 Chemistry Departement, Universty of Texas at Dallas, Richardson, Texas, United States
Show Abstract9:00 PM - Q20.58
Flexible PLED and OLED with Transparent Multiwall Carbon Nanotubes Electrodes.
Raquel Ovalle Robles 1 2 , Sergio Vazquez 1 4 , Christopher Williams 1 2 , Mei Zhang 1 , Shaoli Fang 1 , Sergey Lee 1 , Ray Baughman 1 3 , Anvar Zakhidov 1 2
1 NanoTech, University of Texas at Dallas (UT-D), Plano, Texas, United States, 2 Physiscs Department, University of Texas at Dallas (UT-D), Plano, Texas, United States, 4 Physics Department, Universidad de Guanajuato, Leon, Guanajuato, Mexico, 3 Chemestry Department, University of Texas at Dallas (UT-D), Plano, Texas, United States
Show Abstract9:00 PM - Q20.59
Single Walled Carbon Nanotube Coatings as Transparent Conductors.
Chris Weeks 1 , Michael Trottier 1 , Phillip Wallis 1 , Jorma Peltola 1 , Igor Levitsky 1 , David Britz 1 , Paul Glatkowski 1
1 , Eikos, Inc., Franklin, Massachusetts, United States
Show AbstractTransparent and electrically conductive coatings and films are critical in a variety of applications in the fast-growing flat panel display and photovoltaic industries. The existing standard is wide bandgap semiconducting metal oxides such as indium tin oxide (ITO), and polymers such as poly(3,4-ethylenedioxythiophene) doped and stabilized with poly(styrenesulfonate) (PEDOT/PSS). We have developed an alternative transparent conductor using a network of single wall carbon nanotubes (SWNTs). The optoelectronic properties of these films can be easily tuned to meet a specific conductivity and transparency. We examine conductivity, transparency, color tone neutrality, adhesion, abrasion resistance, and flexibility of these coatings, finding them ideally suited for applications in touch screens, LCDs, OLEDs, and photovoltaics. Additional benefits include ease of solution processing and patterning on glass, plastic, and other substrates.
9:00 PM - Q20.6
Purification of Single-Walled Carbon Nanotubes and the Production of Nanotube/Elastin Composite.
Bin Zhao 1 , Alex Puretzky 1 , Hui Hu 1 , David Styers-Barnett 1 , Ilia Ivanov 1 , Chris Rouleau 1 , David Geohegan 1
1 Center of Nanophase Materials Sciences and the Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
Show Abstract9:00 PM - Q20.60
Fabrication and Magnetic Properties Characterization of Nickel Nanowires Polymer Composite.
Jeongmin Hong 1 , Heather Denver 1 , Diana-Andra Borca-Tasciuc 1
1 Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States
Show Abstract9:00 PM - Q20.61
A Single-walled Carbon Nanotube-based Nanocompass for High Spatial Resolution Magnetometry.
Stephanie Getty 1 , Jonathon Brame 2 , Johnathan Goodsell 2 , Melissa Harrison 4 , Gunther Kletetschka 3 , David Allred 2
1 Materials Engineering Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland, United States, 2 Physics and Astronomy, Brigham Young University, Provo, Utah, United States, 4 Physics, Fisk University, Nashville, Tennessee, United States, 3 Physics, Catholic University, Washington, District of Columbia, United States
Show Abstract9:00 PM - Q20.7
Elastomer Functionalized Carbon Nanofiber for toughening of Poly(siloxaneimide) Based Nanocomposite.
Javed Mapkar 1 , Maria Coleman 1
1 Chemical and Enviornmental Engineering, The University of Toledo, Toledo, Ohio, United States
Show AbstractCarbon nanotubes (CNT)/Carbon nanofibers (CNF) are ideal candidates for polymer reinforcement to enhance electrical and mechanical properties. While functionalization of the CNT/CNF with organic groups is a good way to improve dispersion within polymer matrix, this approach has not lead to dramatic improvement in composite properties. This paper will present results of efforts to modify nanofiber surface with block copolymers with targeted functionality from each block. Specifically, CNF were functionalized with elastomeric block (i.e. aminopropyl terminated polydimethylsiloxane (PDMS-NH2)) and oligomer of polyimide block that mimics structure of matrix polymer. The oligomer block allows for chain entanglement between groups on fiber surface and the elastomeric block is designed to reduce brittleness and improve impact resistance of composite. Functionalization of the CNF was confirmed by X-ray photoelectronic spectroscopy, thermogravimetric analysis and UV-Vis spectroscopy. Two methods were used to incorporate carbon nanofibers of different surface functionality at concentrations up to 1.5 wt % within polymer matrix 1) Blending and 2) In-situ polymerization. Polyimide and 25wt% poly(siloxaneimide) composite were used as the polymer matrix for nanocomposite formation. The carbon nanofibers with the following surface functionality were used in this study: (i) pristine, (ii) oxidized, (iii) 4’-(1,4-Phenylenediisopropylidene) bisaniline (BisP) (iv) PDMS-NH2, (v) polymide oligmer, and (vi) block copolymer. Mechanical testing results showed increases in the modulus, strength and toughness of the polymer with increase in the weight percent of the fibers. The improvement in mechanical properties was dependent on fiber type and loading.
9:00 PM - Q20.8
Low Electrical Resistance of Transparent SWNT/Block Copolymer Thin Films by Incorporating Metal Nanoparticles.
Jinwoo Sung 1 , Cheolmin Park 1
1 Material Science and Engineering, Yonsei Univ., Seoul Korea (the Republic of)
Show AbstractWhile Single wall carbon nanotubes (SWNTs) have electrical superior conductivity, the efforts to apply them to highly conductive film have been retarded by some problems. The very strong van der Waals force among SWNTs with a large area leads to aggregation and comprises a major obstacle for manipulation of thin film. In our system, block copolymer micelles are decorated on the side wall of SWNTs by physical adsorption in solution, wherein entropic repulsion among the corona chain of micelles generates a steric hindrance that prevents SWNTs from approaching the attractive part of the intertube potential. The polymer added for the purpose of dispersion of SWNTs, however, significantly reduces the conductivity of the thin SWNT/polymer film, in which polymer embedded between SWNTs hampers the intertube hopping of charge carriers. In order to improve electrical conductance, we incorporate metal naoparticles which can promote the intertube charge hopping. When precursor is added into the suspension, metal precursor is selectively located in the hydrophilic core of micelle and forms metal nanoparticles upon subsequent reduction. The formation of nanoparticles in the micelles does not deteriorate the SWNT dispersion and results in enhancement of the conductivity in the transparent SWNT/ polymer/metal nanoparticle thin films.
Symposium Organizers
Prabhakar Bandaru University of California-San Diego
Morinobu Endo Shinshu University
Ian Kinloch University of Cambridge
Apparao M. Rao Clemson University
Q21: Biological Interactions of Nanotubes and Nanowires
Session Chairs
Friday AM, December 01, 2006
Room 312 (Hynes)
9:00 AM - **Q21.1
What Carbon Nanotubes and Fullerenes Do when Incorporated in Biological Systems?
Pu-Chun Ke 1
1 , Clemson University, Clemson, South Carolina, United States
Show AbstractIntegrating nanomaterials with biological system is a recent endeavor aiming at providing insights for biological processes, and offering localized detection and treatment avenues. Carbon nanotubes are at the forefront of this grand exploration and research on integrating carbon nanotubes and fullerenes with biological systems will be discussed in my talk. To address the fundamental issue of nanotube solubility, I will present our theoretical and experimental studies on the self assembly of lipids onto carbon nanotubes for enhanced nanomaterial biocompatibility. Through these biophysical studies we have found that zwitterionic lysophospholipids can form highly organized striations on nanotubes to yield a superior solubility. Toward gene delivery, I will discuss the translocation of RNA by nanotube transporters across cell membranes and demonstrate their consequent dissociation in cellular environments using the technique of fluorescence resonance energy transfer, an “optical switch” for detecting lipid-nanotube interaction at the single-molecule level. Recent studies on the ingestion and transport of nanoparticles in a living organism Daphnia magna. will also be discussed which provide insights into nanotoxicity issues. Based on confocal fluorescence imaging we have found that nanoparticles can be taken up from the guts of Daphnia to soft tissues. Finally, I’ll discuss our preliminary studies on the fluorescence properties of water soluble fullerenes C60 and C70 self assembled with lysophospholipids and gallic acids, respectively. Interestingly, these supermolecules show negligible toxicity and distinct green and orange fluorescence in living organisms Daphnia and fat head minnow.
9:30 AM - Q21.2
Interfacing Carbon Nanotubes with Biological Systems.
Xing Chen 1 , Un Chong Tam 1 , David Rabuka 1 , Alex Zettl 2 , Carolyn Bertozzi 1
1 Department of Chemistry, University of California, Berkeley, Berkeley, California, United States, 2 Department of Physics, University of California, Berkeley, Berkeley, California, United States
Show Abstract10:00 AM - Q21.4
Investigation of DNA Decorated Carbon Nanotube Chemical Sensors.
Michelle Chen 1 , Samuel Khamis 2 , Robert Johnson 2 , Cristian Staii 2 , Alex Fried 2 , Michael Klein 3 , John Fischer 1 , Alan Johnson 2
1 Materials Science, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 2 Physics, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 3 Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States
Show AbstractWe demonstrate a versatile class of nanoscale sensors based on single-stranded DNA (ss-DNA) as the chemical recognition site and single-walled carbon nanotube field effect transistors (swCN-FETs) as the electronic readout component. Coating swCN-FETs with ss-DNA causes a current change when exposed to gaseous analytes, whereas bare swCN-FETs show no detectable change. The responses differ in sign and magnitude depending both on the type of gaseous analyte and the sequence of DNA. Our results suggest that the conformation of ss-DNA on swCN-FET plays a role in determining the sensor response to gaseous analytes. The conformation depends not only on the base content of the oligomer, but also on the specific arrangement of the bases in the ss-DNA. We compare our results with the molecular dynamic simulations for understanding of the sensing mechanisms. SsDNA/swCN-FETs possess rapid recovery and self-regenerating ability, which could lead to realization of large arrays for sensitive electronic olfaction and disease diagnosis. This work was supported by the Laboratory for Research on the Structure of Matter (NSF DMR00-79909) and by the US Department of Energy, grant No. DE-FG02-98ER45701 (M.C.).
10:15 AM - Q21.5
Electrochemical Sensing Properties of Ultra Long Aligned Multi-Walled Carbon Nanotube Microelectrodes.
Niramol Punbusayakul 1 2 , Lijie Ci 1 , Saikat Talapatra 1 , Werasak Surareungchai 2 , Pulickel Ajayan 1
1 Materials and Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States, 2 Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkok Thailand
Show Abstract10:30 AM - Q21.6
Highly Improved Sensitivity of Single-Walled Carbon Nanotube Transistor Based Biosensors with Increased Schottky Contact Region.
Hye Ryung Byon 1 , Hee Cheul Choi 1
1 Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang Korea (the Republic of)
Show AbstractA real-time, label-free and electrical detection of biological interactions is one of the core issues for early detection of disease as well as personalized healthcare programs. Electronic devices composed of quantum structures, such as carbon nanotubes, semiconductor nanowires or quantum crystals have great potential to realize these applications successfully. Recently, field effect transistor (FET) devices with carbon nanotubes or Si nanowires as active channels have been demonstrated as a biosensor for the detection of protein-protein interactions. Such devices, especially carbon nanotube FETs have been suffered from low sensitivity (~ 10 to 100 nM). In this presentation, we show successful fabrication of highly sensitive single walled carbon nanotube-FET devices as they reproducibly detect nonspecific protein adsorptions and specific protein-protein interactions at 1 pM concentrations. The detection limit has been improved 4-order compared to the devices fabricated by conventional photolithography. The substantially increased sensitivity is mainly due to the increased Schottky contact area which accommodates relatively more numbers of proteins even at very low concentration. The augmented number of proteins adsorbed on a device induces instant modulation of the work function of metal contact electrodes, which eventually changes the conductance of the device. Such devices have been attained by addressing metal electrodes on network-type CVD grown SWNTs using a shadow mask on a tilted angle sample stage of evaporator. The shadow mask allows metals to penetrate underneath the mask efficiently, therefore forming a thin and wide Schottky contact area on SWNT channels.References* Byon, H. R.; Choi, H. C. J. Am. Chem. Soc. 2006, 128, 2188.* Byon, H. R.; Hong, B. J.; Gho, Y. S.; Park. J. W.; Choi, H. C. ChemBioChem 2005, 6, 1331.* Chen, R.; Choi, H. C. et al. J. Am. Chem. Soc. 2004, 126, 1563.
10:45 AM - Q21.7
Atomic Force Macroscopy of DNA-treated Single Wall Carbon Nano Tubes.
Jie Yang 1 2 , David Kidwell 1 , Pehr Pehrsson 1
1 Surface Science Branch, Naval Research Laboratory, Washington, District of Columbia, United States, 2 , NOVA research Inc., Alexandria, Virginia, United States
Show AbstractQ22: Chemical and Mechanical Interactions
Session Chairs
Friday PM, December 01, 2006
Room 312 (Hynes)
11:30 AM - **Q22.1
Carbon Nanotube – Silicon Heterojunction Hyperspectral Photocurrent Response.
Jimmy Xu 1 , Teng-Fang Kuo 1 , Dan Straus 1 , Marian Tzolov 1 2
1 , Brown University, Providence, Rhode Island, United States, 2 Dept. of Geology and Physics, Lock Haven University, Lock Haven, Pennsylvania, United States
Show Abstract12:15 PM - Q22.3
Thermotropic and Lyotropic Liquid Crystals: Self-organizing Media to Organize Carbon Nanotubes.
Giusy Scalia 1 2 , Jan Lagerwall 3 , Miroslav Haluska 1 , Ursula Dettlaff-Weglikowska 1 , Frank Giesselmann 3 , Siegmar Roth 1
1 Department von Klitzing, Max Planck Institute, Stuttgart Germany, 2 , ENEA, Portici (Naples) Italy, 3 Institute of Physical Chemistry, Universität Stuttgart, Stuttgart Germany
Show Abstract12:30 PM - Q22.4
Multiscale Modeling of Mechanics of Carbon Nanotubes: Self-assembly, Self-folding and Fracture.
Markus Buehler 1 , Ryan King 1 , Cindy Wang 1
1 Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractUsing concepts of hierarchical multi-scale modeling, we report development of a mesoscopic model for single wall carbon nanotubes with parameters completely derived from full atomistic simulations. The parameters in the mesoscopic model are fit to reproduce elastic, fracture and adhesion properties of carbon nanotubes, here demonstrated for (5,5) carbon nanotubes. The mesoscale model enables to model the dynamics of systems with hundreds of ultra-long carbon nanotubes over time scales approaching microseconds. We apply our mesoscopic model to study self-assembly processes, including self-folding, bundle formation, as well as the response of bundles of carbon nanotubes to severe mechanical stimulation under compression, bending and tension. Our results with mesoscale modeling corroborate earlier results suggesting a novel self-folding mechanism, leading to creation of racket-shaped carbon nanotubes structures provided that the aspect ratio of the carbon nanotube is sufficiently large. We find that the persistence length of the (5,5) carbon nanotube is on the order of a few µm in the temperature regime from 300K to 1000K. We further present results of atomistic modeling carbon nanotubes using a new first principles based reactive force field. This model allows to study the effects of hydrogen, oxygen and water molecules on the deformation behavior. We report preliminary results of this mechanics-chemical coupling.
12:45 PM - Q22.5
Elastic Property of Vertically Aligned Nanowires
Jinhui Song 1 , Xudong Wang 1 , Elisa Riedo 2 , Zhong Wang 1
1 Materials Science & Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States, 2 Physics, Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractWe present a new approach for measuring the mechanical properties of aligned nanowires of ZnO without manipulating or destructing [1]. An atomic force microscopy (AFM) based technique is demonstrated for measuring the elastic modulus of individual nanowires/nanotubes aligned on a solid substrate . By simultaneously acquiring the topography and lateral force image of the aligned nanowires in the AFM contacting mode, the elastic modulus of the individual nanowires in the image has been derived. The topography records the individual nanowire’s height and the maximum bending distance which is caused by the scanning AFM tip. The lateral force image records the maximum force applied by the scanning AFM tip. Based on these information, Young’s modulus of each individual aligned ZnO nanowire could be caculated. The measurement is based on one scan of AFM in contact mode. For the [0001] ZnO nanowires/nanorods grown on a sapphire surface with an average diameterof 45 nm, the elastic modulus is measured to be 29 ± 8 GPa. The technique has two advantages. One, it is feasible to measure the elastic modulus of an as-grown nanowire without destructing the sample. Secondly, the measurements are carried out individually, systematically and almost simultaneously for all of the nanowires aligned in the scanning range of the AFM tip, whose lengths can be different.
[1] J.H. Song, X.D. Wang, E. Riedo and Zhong L. Wang, Nano Letters, 5 (2005) 1954.
[2] for details visit: www.nanoscience.gatech.edu/zlwang
Q23: Mechanical Properties & Modeling
Session Chairs
Friday PM, December 01, 2006
Room 312 (Hynes)
2:30 PM - **Q23.1
Nano-Electromechanical Systems based on Single-Walled Carbon Nanotubes.
Jannik Meyer 1 , Dirk Obergfell 1 , Matthieu Paillet 2 , Thierry Michel 2 , Jean-Louis Sauvajol 2 , Siegmar Roth 1
1 , Max-Planck Institute for solid state research, Stuttgart Germany, 2 Laboratoire des Colloides, Verres et Nanomateriaux, Universite de Montpellier II, Montpellier France
Show Abstract3:00 PM - **Q23.2
Electron Localization in Tensile Elongated Carbon Nanotubes.
Jianyu Huang 1 , S. Chen 1 , Z. Wang 1 , Z. Ren 1 , K. Kempa 1 , M. Naughton 1 , G. Chen 2 , M. Dresselhaus 3
1 Physics, Boston College, Chestnut Hill, Massachusetts, United States, 2 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 3 Department of Physics, Electrical Engineering and Computer Science, , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show Abstract3:30 PM - Q23.3
Multi-walled Carbon Nanotube based Shear Sensors: Theory, Design, and Synthesis.
Christian Deck 1 , Chi-Nung Ni 1 , Kenneth Vecchio 1 , Prabhakar Bandaru 1
1 , UC San Diego, La Jolla, California, United States
Show Abstract3:45 PM - Q23.4
Nanomechanical Oscillator Arrays Fabricated by Bottom-up Integration of Silicon Nanowires.
Mingwei Li 1 , Rustom Bhiladvala 1 4 , James Sioss 2 , Kok-Keong Lew 3 , Joan Redwing 3 1 , Christine Keating 2 , Theresa Mayer 1
1 Electrical Engineering, Penn State University, University Park, Pennsylvania, United States, 4 Materials Research Institute, Penn State University, University Park, Pennsylvania, United States, 2 Chemistry, Penn State University, University Park, Pennsylvania, United States, 3 Materials Science and Engineering, Penn State University, University Park, Pennsylvania, United States
Show AbstractQ24: Nanocomposites & Large Scale Use of NW/NTs
Session Chairs
Friday PM, December 01, 2006
Room 312 (Hynes)
4:30 PM - **Q24.1
Optical and Optoelectronic Properties of Nanowire and Nanotube / Polymer Composites A Model Study in NanoscaleMolecular Engineering
Werner Blau 1
1 School of Physics , Trinity College Dublin, Dublin Ireland
Show Abstract5:00 PM - Q24.2
Direct Growth of Carbon Nanotubes on Metal-Doped Carbon Aerogels: Novel Composite Materials and a Novel Method for Characterizing a Metal’s Propensity to Catalyze Nanotube Growth.
Stephen Steiner III 1 , Theodore Baumann 2 , Joe Satcher Jr. 2 , Mildred Dresselhaus 3 4 , Jing Kong 3
1 Research Laboratory of Electronics, MIT, Cambridge, Massachusetts, United States, 2 Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States, 3 Department of Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts, United States, 4 Department of Physics, MIT, Cambridge, Massachusetts, United States
Show Abstract5:15 PM - Q24.3
Nanocomposite Polymer Foams Containing Carbon Nanotubes and Nanofibres.
Milo Shaffer 1 , Raquel Verdejo 1 , Alexander Bismarck 1 , Jan Sandler 2 , Volker Altstädt 2
1 Dept of Chemistry, Imperial College London, London United Kingdom, 2 , University of Bayreuth, Bayreuth Germany
Show AbstractCarbon nanotubes and nanofibres have intrinsic potential to reinforce fine structures where other reinforcements cannot be accommodated. For example, previous work has demonstrated that nanofibre-reinforced polymer fibres have improved mechanical properties, attributable both to the filler and to changes in polymer morphology. One underexploited opportunity is the use of high aspect ratio nanofillers to reinforce polymer foams. This presentation will discuss a number of processing routes that have been developed, and will shown that the nanofiller can both aid processing and improve the resulting properties of the composite.The first case concerns thermoplastic processing of poly(ether ether ketone) (PEEK), a high performance polymer that cannot normally be foamed, due to melt instability. In this case, melt elongation measurements indicate that CNFs, unlike graphite controls, significantly increase the melt strength of PEEK, stabilising bubble growth. This rheological change allows straightforward fabrication of high quality PEEK foams, with nanofibres uniformly distributed throughout the cell walls and struts. The presence of the nanofiller provides property enhancements, for example, raising the specific strength and stiffness of foam injection moulded samples in bending.The second case concerns reactive polyurethane foaming; with appropriate functionalisation and dispersion, high quality open-celled foams can be prepared, with interesting properties, both functional and mechanical.Lastly, a range of solution-based and templating methods can be exploited to produce open-celled porous structures with unusual structural features.
5:30 PM - Q24.4
Simulation of the Stress–strain Behavior of Single and Multiwall Carbon Nanotubes-reinforced Polymer Composites.
Antonio Pantano 1 , David M. Parks 2 , Mary C. Boyce 2 , Francesco Cappello 1
1 Dipartimento di Meccanica, University of Palermo, Palermo Italy, 2 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show Abstract5:45 PM - Q24.5
Solid State Spinning of Carbon Nanotube Yarns.
Shaoli Fang 1 , Mei Zhang 1 , Ken Atkinson 2 , Ray Baughman 1
1 Nanotech Institute, University of Texas at Dallas, Richardson, Texas, United States, 2 , CSIRO Textile & Fibre Technology, Victoria, Australian Capital Territory, Australia
Show Abstract