Symposium Organizers
Wei Zhao University of Arkansas
Pehr E. Pehrsson Naval Research Laboratory
Stephen K. Doorn Los Alamos National Laboratory
Jie Liu Duke University
Phaedon Avouris IBM T. J. Watson Research Center
Symposium Support
Army Research Office
EE1/DD1: Joint Session: Synthesis of Nanotubes and Nanowires
Session Chairs
Monday PM, April 09, 2007
Room 2001 (Moscone West)
9:00 AM - EE1.1/DD1.1
Controlling Growth of Carbon Nanotubes for Devices
John Robertson 1 , Stephan Hofmann 1 , Mirco Cantoro 1 , Guofang Zhong 1
1 Engineering, Cambridge University, Cambridge United Kingdom
Show AbstractCarbon nanotubes have unique properties which may lead to their use in high performance electronic devices such as vias, interconnects and FETs. However, these applications require a much better control of the growth process than presently exists. For Vias formed by a bunch of multi-walled nanotubes, the effective resistance must be reduced to 10 ohms. Unless the contact resistance is very low, this requires growth of very closely spaced MWNTs. MWNTs grown by PECVD or CVD are typically grown from a Ni or Fe which has been restructured into a nano-particle from which the nanotube nucleates. But this tends to restrict the site density. On the other hand, FETs require use of only semiconducting single wall nanotubes, which in effect requires some chiral selection, or post-growth separation, which is uneconomic. Both applications place temperature limits on the growth process. We have shown by recent work an improved understanding of the growth process which helps in each of these aspects, such as the ability to grow SNWTs at only 350C by purely thermal CVD [2], and the highest nucleation density and catalyst efficiency of vertically aligned SWNT mats [3].1 S Hofmann, et al, App Phys Lett 83 135 (2003); J App Phys 98 034308 (2005)2 M Cantoro et al, Nanolett 6 1107 (2006)3 G Zhong et al, Carbon 44 2009 (2006)
9:15 AM - EE1.2/DD1.2
Combinatorial Control of Catalysts for Carbon Nanotube Growth: From Sparse Networks for Transparent Electrodes to Dense Forests for Mass Production
Suguru Noda 1 , Hisashi Sugime 1 , Kei Hasegawa 1 , Ryuhei Itoh 1 , Shingo Morokuma 1 , Kazunori Kakehi 1 , Toshio Osawa 1 , Shigeo Maruyama 2 , Yukio Yamaguchi 1
1 Department of Chemical System Engineering, The University of Tokyo, Tokyo Japan, 2 Department of Mechanical Engineering, The University of Tokyo, Tokyo Japan
Show AbstractFor single-walled carbon nanotubes (SWNTs), various applications have been proposed and intensively studied. To realize high-value-added devices such as integrated circuits, many development challenges still exist in the structural control from the chirality of individual SWNTs to the position and orientation of numerous short SWNTs. On the other hand, if the SWNTs can be grown at a low cost, other applications such as transparent conducting films may be realized with fewer innovations in processing technology. In this paper, we applied our combinatorial method [1,2] for catalyst screening and grew SWNTs on substrates at various areal densities and lengths. Co-Mo binary catalysts are known effective to grow SWNTs either from CO and C2H5OH. However, different values are reported as the optimum Co/Mo atomic ratio; 1/3 for the former [3] and 1/1 for the latter [4]. We grew SWNTs from C2H5OH at 1073 K and 0.4-4 kPa for 3-30 min on a catalyst library with orthogonal thickness profiles of 0.01-0.8 nm Co and 0.03-2 nm Mo. Both of those two regions proved catalytically active, and in addition, another region with a large Co/Mo ratio became active at 4 kPa after a few minute incubation time where nanotubes containing SWNTs grew rapidly. By controlling reaction and catalyst conditions, the areal density and length of nanotubes can be controlled. Films of bundled, networked nanotubes show optical and electrical properties depending on the structure. For example, a nanotube film on a quartz glass substrate showed a 85 % transmittance and a 8 kΩ/sq. sheet resistance, whereas a film with a larger nanotube length and a lower areal density showed a 92 % transmittance and a 2 kΩ/sq. sheet resistance. Properties of nanotube films can be tailored in this way.Fe/Al2O3 can rapidly grow SWNTs from C2H4 when a small amount of H2O is added [5]. We applied our combinatorial method to this reaction system. The Fe/Al2O3 catalyst library grew nanotubes of various diameters and the nanotube yield was largely dependent on the nominal Fe thickness. Millimeter-thick films of nanotubes containing SWNTs were formed in 10 min after a complicated optimization among partial pressures of C2H4, H2 and H2O and temperature. Some of these films can be easily separated from the substrate, and this growth mode may be applied for the mass production of SWNTs. [1] S. Noda, et al., Appl. Phys. Lett. 86, 173106 (2005).[2] S. Noda, et al., Carbon 44, 1414 (2006).[3] J.E. Herrera, et al., J. Catal. 204, 129 (2001).[4] Y. Murakami, et al., Chem. Phys. Lett. 385, 298 (2004).[5] K. Hata, et al., Science 306, 1362 (2004).
9:30 AM - EE1.3/DD1.3
Dependence of Carbon Nanotube (CNT) Length and Growth Rate upon Temperature in the Growth of CNT by Metal-catalyzed Chemical Vapor Deposition.
Michael Bronikowski 1
1 Jet Propulsion Laboratory
, California Institute of Technology, Pasadena, California, United States
Show Abstract9:45 AM - EE1.4/DD1.4
Control of Catalyst Nanoparticles for Selective CVD Growth of Carbon Nanotubes.
Yunyu Wang 1 , Bin Li 1 , Zhiquan Luo 1 , Li Shi 2 , Zhen Yao 3 , Eugene Bryan 4 , Robert Nemanich 5 , Paul Ho 1 2
1 Microelectronics Research Center, The University of Texas at Austin, Austin, Texas, United States, 2 The Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas, United States, 3 The Department of Physics, The University of Texas at Austin, Austin, Texas, United States, 4 The Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina, United States, 5 The Department of Physics, North Carolina State University, Raleigh, North Carolina, United States
Show Abstract10:00 AM - EE1.5/DD1.5
Synthesis and Structural Characterization of Aligned Carbon Nanotubes on Sapphire and Quartz Substrates
Lewis Gomez 1 , Bo Lei 2 , Koungmin Ryu 2 , Alexander Badmaev 2 , Xiaolei Liu 2 , Steve Cronin 2 , Chongwu Zhou 2
1 Chemistry, USC, Los Angeles, California, United States, 2 Electrophysics, USC, Los Angeles, California, United States
Show AbstractSynthesis of massively aligned single-walled carbon nanotubes has stimulated significant interest due to their potential for integrated nanotube circuits and systems. Despite recent success on the synthesis, there is still a lack of study on the influence of the substrate on the structural and ultimately physical properties of the nanotubes. In this talk we will present our recent advance in aligned nanotube synthesis and also in-depth Raman characterization of the nanotubes obtained. The synthesis of aligned nanotubes was achieved using a chemical vapor deposition technique with Ferritin as the catalyst and a-plane sapphire and mistcut quartz as the substrates. Simultaneous control over the nanotube orientation and position has also been achieved by patterning catalyst at desired sites on the crystalline substrates. The nanotubes on a-plane sapphire were found to lie normal to the c-axis of the substrate, while the nanotubes on quartz followed the step edges of the miscut substrates. AFM and SEM microscopy combined with vibrational resonantly enhanced micro Raman characterization was proved to be a powerful tool to structurally characterize the samples at the single nanotube level. We use three different laser energies to determine diameter distribution and non-nanotube carbon impurities. The metallic to semiconducting ratio analysis of the carbon nanotubes revealed a metallic nanotube content of ~ 27%. Polarized Raman spectra of nanotubes showed a suppression of the C=C stretching mode when the laser electric field axis was perpendicular to the nanotubes principal axis. Furthermore, electrical properties on nanotubes produced on the different substrates were evaluated. Our results demonstrate that the surface molecular arrangement of the substrate as well as surface-carbon interactions play an important role in the properties of the synthesized nanotubes.
10:15 AM - EE1.6/DD1.6
Influence of Hydrogen Level During the Growth Process on the Properties of Single-wall Carbon Nanotubes.
Alexandru Biris 1 2 , Alexandru Biris 3 , Dan Lupu 3 , Zhongrui Li 2 , Enkeleda Dervishi 1 2 , Viney Saini 1 2
1 Applied Science , University of Arkansas at Little Rock, Little Rock, Arkansas, United States, 2 Nanotechnology Center, University of Arkansas at Little Rock, Little Rock, Arkansas, United States, 3 , National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj Napoca Romania
Show Abstract10:30 AM - EE1.7/DD1.7
High Yield Multiwall Carbon Nanotube Synthesis in Supercritical Fluids
Danielle Smith 1 , Doh Lee 1 , Brian Korgel 1
1 Chemical Engineering, University of Texas at Austin, Austin, Texas, United States
Show AbstractMultiwall carbon nanotubes (MWNTs) were synthesized in supercritical toluene at temperatures ranging from 600 to 645 °C at 8.3 MPa using ferrocene, cobaltocene, nickelocene, Fe, and Co nanocrystals as catalysts. A continuous flow reactor was used to produce nanotubes with outer diameters of 10 - 50 nm and wall thicknesses of 5 - 20 nm.In this supercritical fluid synthesis, toluene served as both the solvent and the primary carbon source for nanotube formation. We also discovered that supplemental carbon sources, either hexane or ethanol (30 vol %), increased the yield of the carbon nanotubes relative to pure toluene by almost an order of magnitude. Additionally, catalytic amounts of water (0.75 vol %) minimized the formation of carbon filaments and amorphous carbon deposition. Cobalt and nickel precursors in addition to the use of a continuous flow reactor led to much higher yields than previous batch reactions in supercritical toluene. Using cobaltocene as a catalyst, with ethanol as a supplemental carbon source, gave the highest percentage of nanotubes in the product (70%) and the highest conversion of toluene to MWNTs (4%). Cobaltocene was also the best catalyst in terms of purity of the product with the highest proportion of carbon nanotubes produced relative to carbon filaments and amorphous carbon. These observations might be explained by examining the phase diagrams, which report higher carbon solubility into Co compared to Ni and Fe at temperatures of 600 to 650 °C.The MWNTs generated in this supercritical fluid system tended to exhibit bamboo morphology and appear to grow by a folded-growth mechanism with graphitic sheets wrapped around the seed metal particles. Many MWNTs exhibited significant defects in their graphitic layers, resulting in curly and kinked nanowires. In some cases where cobaltocene was used as a catalyst, the nanowire bending was consistent along the length of the nanotube, resulting in coiled nanotube formation, with the appearance of springs, hairpins, lassos, and coiled ropes. In future work, conditions might be identified that will enable SWNT synthesis.
10:45 AM - **EE1.8/DD1.8
Synthesis and Applications of Classes of Non-carbonaceous Nanostructures.
Stanislaus Wong 1 2
1 Department of Chemistry, SUNY Stony Brook, Stony Brook, New York, United States, 2 Condensed Matter Physics and Materials Sciences Department, Brookhaven National Laboratory, Upton, New York, United States
Show Abstract11:15 AM - EE1/DD1: Synt
Break
11:30 AM - **EE1.9/DD1.9
Nanowires and Nanotubes Synthesized in Solution: Their Chemistry, Twins and Branching.
Brian Korgel 1
1 Chemical Engineering, University of Texas at Austin, Austin, Texas, United States
Show Abstract12:00 PM - EE1.10/DD1.10
Alternative Catalysts For Si-Technology Compatible Growth Of Si Nanowires.
Francesca Iacopi 1 , Philippe Vereecken 1 , Nele Moelans 2 , Bart Blanpain 2 , Hefin Griffiths 3
1 , IMEC, Leuven Belgium, 2 MTM, Katholieke Universiteit Leuven, Leuven Belgium, 3 , Oxford Instruments, Bristol United Kingdom
Show AbstractAu has been widely demonstrated in literature as an efficient metal catalyst for the growth of semiconducting nanowires [1]. Also metals such as Ag, Cu, Pd have been shown to be efficient catalysts for growth of Si whiskers [2]. Nevertheless, from a Si semiconductor technology point of view, most of those are undesired metals, either because their diffusion into bulk silicon leads to the formation of mid gap states [3], or because they react with Si, leading to uncertainties on the final stechiometry of the precipitate. In order to allow a viable evolutionary path from the conventional planar CMOS technologies to 1D nanowire –based devices, alternative catalyst materials more compatible with Si and allowing nanowire growth at temperatures at least around or below 500○C need to be established.In this context, feasibility for growth of Si nanowires catalysed by Indium nanoparticles was investigated. Indium shows several advantages: does not react with Si, is compatible with Si technology (it is used as p-type dopant material), and is also a thermodynamically favourable catalyst for Si nanowhisker growth according to the Vapor-Liquid-Solid (VLS) theory. Indeed, the In-Si system has a low eutectic temperature (157○C) with low Si solubility (0.004%). On the other hand, Indium is not an efficient catalyst for the dehydrogenation reaction of SiH4, reason why early attempts for Si nanowires growth with In nanoparticles were not successful [2]. Growth experiments were conducted in a Plasma Enhanced Chemical Vapour Deposition system onto (100) Si, previously electroplated with In nanoparticles with diameter ranging roughly between 200nm and 30nm. Slightly tapered Si nanowires were grown at rather high rate (~300nm/min) at 500○C, using silane as precursor gas and low RF power (5W). Tip growth was recognized from the almost spherical In particles observed on the top of the whiskers, in agreement with the VLS model. In addition to In, the efficiency of other Si –compatible metal catalysts such as Al, Sb, Ga is currently under investigation. The selection of the catalyst system will be extended to favourable alloys/compounds by means of thermodynamics calculations of ternary systems with Si. Feasibility for SiGe nanowire growth using the same catalysts will also be investigated.[1] R.S.Wagner, W.C.Ellis, Appl.Phys.Lett. 4 (5), pp.89-90, 1964[2] G.A.Bootsma, H.J.Gassen, J.Crystal Growth 10, pp.223-234, 1971 [3] S.M.Sze, Physics of Semiconductor Devices, Wiley Interscience, New York, 1981
12:15 PM - EE1.11/DD1.11
Plasma-stimulated Control of Silicon Nanowire Nucleation, Orientation and Growth Kinetics.
Pavan Reddy Aella 1 4 , W. Petuskey 1 4 , S. Picraux 2 3 4
1 Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona, United States, 4 Science and Engineering of Materials Graduate Program, Arizona State University, Tempe, Arizona, United States, 2 Department of Chemical and Materials Engineering, Arizona State University, Tempe, Arizona, United States, 3 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show Abstract12:30 PM - EE1.12/DD1.12
Quantitative Determination of the Nucleation Kinetics of Si Nanowires.grown on Si3N4 substrates by the VLS mechanism
Bong-Joong Kim 1 , Suneel Kodambaka 2 , Mark Reuter 2 , Kathy Reuter 2 , Eric Stach 1 , Frances Ross 2
1 Eric Stach, Purdue University, West Lafayette, Indiana, United States, 2 , IBM Watson Research Center, Yorktown Heights, New York, United States
Show Abstract12:45 PM - EE1.13/DD1.13
Self-assembled Tm Silicide Nanowires on Si(001) Studied by STM and TEM.
Jiaming Zhang 1 , M. Crimp 1 , Yan Cui 2 , J. Nogami 2
1 Department of Chemical Engineering and Materials Science, Michigan State University, East lansing, Michigan, United States, 2 Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario, Canada
Show AbstractSelf-assembled rare earth (RE) metal silicide nanowires are promising for application in future nano interconnects and devices. Since the formation of epitaxial silicide nanowires by deposition of RE metals on Si(001) was first discovered, intense interest has been focused on the epitaxial growth mechanism of RE silicides on Si surfaces. Our recent work has shown that Tm silicides form epitaxial nanowires on Si(001). Unlike many of the other nanowire forming RE metals, which have several different polymorphic silicides at about the same stoichiometry, Tm forms three bulk silicides Tm5Si3,TmSi, and Tm3Si5 with very different compositions and crystal structures. The latter two phases the potential for nanowire formation. Scanning tunneling microscopy (STM) shows many 3D nanowires with some larger square islands. However, the structures of the nanowires seem to be more complex than in the case of other RE silicides. Surface reconstructions on these indicate strain relief mechanisms within these wires. Plan-view and cross-sectional high resolution transmission electron microscopy (HRTEM) results will be used to correlate silicide crystal structure to island and nanowire morphology.
EE2/DD3: Joint Session: Synthesis of Nanotubes and Nanowires II
Session Chairs
Monday PM, April 09, 2007
Room 2001 (Moscone West)
2:30 PM - EE2.1/DD3.1
Growth of SiC Nanowires in Different Directions on Sapphire Substrates
Qingkai Yu 1 , Shin-Shem Pei 1 , Jian Shi 2 , Hao Li 2
1 , Univ of Houston , Houston, Texas, United States, 2 , University of Missouri, Columbia, Missouri, United States
Show AbstractFree-standing SiC nanowires and SiC nanowires on R-plane sapphire substrates were grown by chemical vapor deposition. SiO vapor and various carbon sources are the precursors for the formation of SiC nanowires. The morphology and composition were characterized by SEM, TEM, AFM, and XPS. TEM results demonstrate that the nanowires have a core-shell structure. It was also found that the diameter of SiC nanowires influence the morphology of both free-standing SiC nanowires and the ones on sapphire substrates. The directions of SiC nanowires grown on R-plane sapphire substrates are affected by precursors, experimental conditions, and the substrates. At the end, the electrical properties and potential applications are also discussed.
2:45 PM - EE2.2/DD3.2
Thermodynamics and Kinetics of Germanium Nanowire Nucleation and Growth
Hemant Adhikari 1 , Paul McIntyre 1 , Christopher Chidsey 2 , Ann Marshall 3
1 Materials Science and Engineering, Stanford University, Stanford, California, United States, 2 Chemistry, Stanford University, Stanford, California, United States, 3 Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California, United States
Show AbstractIn 3-dimensional nanoelectronics, vertically aligned nanowires have been proposed to provide a solution to attain ultra high density nanoscale device arrays. We have demonstrated the growth of vertically aligned single-crystal germanium nanowires (GeNWs) at temperatures of 400°C or less by metal nanoparticle-catalyzed chemical vapor deposition. We found that temperatures close to bulk eutectic of Au-Ge are required for efficient nucleation of epitaxial nanowires on Ge substrates, but the subsequent growth of nanowires can be carried out at temperatures as low as 270°C. To understand the nucleation of nanowires from gold catalyst particles and to test whether the Vapor-Liquid-Solid mechanism is actually responsible for the growth of nanowires, it is important to understand the phase equilibrium between Au nanoparticles and germanium. Capillary effects, often represented by the Gibbs-Thomson pressure, increase the free energy of the nanoparticle catalyst and the nanowire relative to their bulk values and hence cause lower the eutectic temperature. NW nucleation, where the catalyst nanoparticle is initially in contact with a flat Ge surface, and NW growth, where it is in contact with a GeNW, are very different situations. We have calculated the equilibrium phase diagrams for both the Au-rich liquid nanoparticle in contact with flat Ge (nucleation) and Au-rich liquid nanoparticle in contact with nanowire (growth) cases. The Gibbs-Thomson pressure effect is estimated to be insufficient to stabilize a liquid at the temperatures at which we observe stable Ge NW growth. However, we have also derived limiting expressions for the metastable liquidus for the Au-Ge binary system when a nano-scale liquid droplet is supersaturated with Ge during GeNW growth. Results obtained from these calculations suggest that much larger undercoolings of a Au-Ge liquid are possible during Ge NW growth, consistent with our experimental observations. Ex-situ heating and cooling behavior of germanium nanowires of different diameters (without Ge deposition) was observed inside a transmission electron microscope column. We noted that temperatures close to bulk eutectic were required for the Au tip of nanowire to melt and form a eutectic alloy with the GeNW during the heating cycle. But, when cooling from a high temperature, the liquid alloy remained stable for an under-cooling of the order of 100°C. These ex-situ TEM heating/cooling results suggest that a substantial undercooling of the liquid below the bulk eutectic temperature may also arise because of the barrier associated with nucleating solid Au. A critical assessment of the importance of the Au nucleation barrier versus Ge supersaturation of the Au-Ge catalyst particle in maintaining a liquid catalyst at large undercoolings will be presented.
3:00 PM - EE2.3/DD3.3
Vapor-liquid-solid Growth of Ge Nanowires at Temperatures Below the Eutectic Temperature.
Suneel Kodambaka 1 2 , Jerry Tersoff 1 , Kathleen Reuter 1 , Frances Ross 1
1 Physical Sciences, IBM T. J. Watson Research Center, Yorktown Heights, New York, United States, 2 Materials Science and Engineering, University of California, Los Angeles, California, United States
Show Abstract3:15 PM - EE2.4/DD3.4
Growth of Boron Nanowires by Chemical Vapor Deposition
Li Guo 1 , Raj Singh 1
1 Chemical and Materials Engineering, University of Cincinnati, Cincinnati, Ohio, United States
Show AbstractMotivated by the extensive research on carbon nanotubes (CNTs), boron and its related nano-structures have attracted increasing interests for potential applications in nanodevices and nanotechnologies due to their extraordinary properties. B-related nanostructures are successfully grown on various substrates in a CVD process. The boron nanowires have diameters around 20-200 nanometers and lengths up to microns. Icosahedra B12 is shown to be basic building unit forming the B nanowires by Raman. The gas chemistry is monitored by the in-situ mass-spectroscopy, which helps to identify reactive species in the process. A nucleation controlled growth mechanism and VLS growth are proposed for the growth of these nanostructures. The role of the catalysts in the synthesis is also discussed.
3:30 PM - EE2.5/DD3.5
Plasmon-assisted Local Growth of Individual Semiconductor Nanowires
Linyou Cao 1 2 , David Barsic 1 2 , Alex Guichard 1 2 , Mark Brongersma 1 2
1 Department of Materials Science and Engineering, Stanford University, Stanford, California, United States, 2 Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California, United States
Show AbstractControlled growth of individual semiconductor nanowires (NWs) at well-defined and pre-specified locations will greatly simplify the integration of such NWs into device architectures. It can also prevent possible processing-induced damage to the nanowires common in conventional nano-fabrication process. Conventional chemical vapor deposition (CVD) growth typically produces many nanowires simultaneously in a high-temperature environment and device fabrication requires the use of complex post-processing methods. Here, we demonstrate a new technology capable of locally depositing heat in a pre-specified metal particle. To this end, a low power (~10mW), focused laser beam is used to illuminate a Au nanoparticle layer generated by evaporation and annealing. The laser wavelength is chosen to match the surface plasmon resonance frequency of the Au particles, such that the electromagnetic energy is efficiently converted to heat. Growth occurs when 2% SiH4 in Ar gas is delivered to this heated area. The high temperature region is confined to the immediate viscinity of the heated particle with the environment remaining at room temperature. The observed results are in agreement with a thermal model that predicts the temperature distribution around an illuminated Au particle for a certain laser power density and spot size. This work could have a major impact on the field of nanoparticle catalysis and growth and enable new NW-based devices to be realized.
3:45 PM - EE2.6/DD3.6
Growth Direction Control in Zinc Oxide Nanowires
Husnu Unalan 1 , Pritesh Hiralal 1 , Yang Yang 1 , Tim Butler 1 , Nalin Rupesinghe 1 , Ken Teo 1 , Gehan Amaratunga 1
1 Electrical Engineering Division, Engineering Dept., University of Cambridge, Cambridge United Kingdom
Show AbstractGrowth direction control of nanowires is essential in determining the integration density as well as positioning of the nano scale devices. In this work, we have utilized electric field during growth of zinc oxide (ZnO) nanowires by chemical vapor deposition for the control of growth direction. Both lateral and vertical growth results will be described. The alignment techniques used follow from those developed for deterministic growth of single walled [1] and multi walled [2] carbon nanotubes. Electric field inside the plasma sheath is exploited for vertical alignment, whereas an auxiliary DC is applied to generate the field for the lateral alignment. We have analyzed the as-grown ZnO nanowires with scanning electron microscopy, transmission electron microscopy, photoluminescence and electrical measurements. In brief, the work reported is a step towards integration of ZnO nanowires in nanoscale electronic and optoelectronic devices. [1] Y. Zhang, A. Chang, J. Cao, Q. Wang, W. Kim, Y. Li, N. Morris, E. Yenilmez, J. Kong, H. Dai, Appl. Phys. Lett 79 (2001) 3155.[2] M. Chhowalla, K. B. K. Teo, C. Ducati, N.L. Rupesinghe, G.A.J. Amaratunga, A.C. Ferrari, D. Joy, J. Robertson, W. I. Milne, J. Appl. Phys. 90 (2001) 5308.
4:00 PM - EE2/DD3: Synt
Break
4:15 PM - EE2.7/DD3.7
Synthesis and Photoluminescence Properties of Ultrathin Alumina-coated ZnO Nanotubes Grown on Si Wafer.
Chi-Sheng Hsiao 1 , San-Yuan Chen 1 , Wan-Lin Kuo 1
1 Department of materials science and engineering, National Chiao Tung University, Hsinchu Taiwan
Show Abstract4:30 PM - EE2.8/DD3.8
Formation and Applications of Biphasic GaN Nanowires as a Function of Growth Parameters.
Kaylee McElroy 1 , Benjamin Jacobs 1 , Andrew Baczewski 1 , Virginia Ayres 1 , Joshua Halpern 2 , Mao He 2 , Mihail Petkov 3 , Martin Crimp 1 , Harry Shaw 4
1 College of Engineering, Michigan State University, East Lansing, Michigan, United States, 2 Department of Chemistry, Howard University, Washington D. C., District of Columbia, United States, 3 , NASA Jet Propulsion Laboratory, Pasadena, California, United States, 4 , NASA Goddard Space Flight Center, Greenbelt, Maryland, United States
Show Abstract4:45 PM - EE2.9/DD3.9
Single-Crystalline Nanotubes of II3-V2 Semiconductors.
Guozhen Shen 1 , Yoshio Bando 1 , Dmitri Golberg 1
1 Nanoscale Materials Center, National Institute for Materials Science, Tsukuba Japan
Show AbstractIn recent years, considerable attention has been paid to 1-D nanostructures owing to their unique physical and chemical properties, and potential applications in nanoscale devices with diverse functions [1]. Semiconducting II3-V2 compounds are of great scientific and technological importance. Due to the large excitonic radii of these materials, they are expected to exhibit pronounced size quantization effects. The electrons in such a semiconductor will become confined in crystals much larger than for the analogous II-VI or III-V semiconductors. However, compared with the significant progress in 1-D nanoscale II-VI and III-V semiconductors, research on nanoscale II3-V2 semiconductors has been lingering far behind because of the lack of appropriate and generalized synthetic methodologies [2]. Herein, we report the first synthesis of single-crystalline II3-V2 nanotubes, Cd3P2 and Zn3P2 nanotubes, by thermal evaporation a mixture of ZnS (or CdS), P, and Mn3P2 powders in a vertical induction furnace [3] by a self-sacrificing template process, in which the in-situ formed Cd or Zn nanorods act as the self-sacrificing templates for the growth of nanotubes. By carefully controlling the experimental parameters, II3-V2 nanotubes based 1D heterostructures are also fabricated using this simple method [4].After reaction, XRD results indicate the formation of pure Zn3P2 and Cd3P2 structures. The morphology and composition of the synthesized products were checked using SEM, TEM and EDS. The results reveal the formation of smooth Cd3P2 nanotubes with outer diameters of 80-250 nm and Zn3P2 nanotubes with outer diameters of 100-200 nm. All the nanotubes have circular cross-sections, open ends without any attached particles, uniform diameters along their entire lengths and very thin walls compared to hollow cavities. HRTEM images shows the clearly marked interplanar d-spacing of 0.35 nm for Cd3P2 and 0.33 nm for Zn3P2, corresponding to that of the {202} lattice planes of tetragonal Cd3P2 and Zn3P2, respectively. Besides the pure nanotubes, some partially filled nanotubes were also observed. Series of experimental results give a self-sacrificing template mechanism of these nanotubes.Cathodoluminescence (CL) properties of II3-V2 nanotubes were briefly studied here at 16 K. Zn3P2 nanotubes with wall thickness of ca. 10 nm, 20 nm and 45 nm, show emissions centered at about 491 nm, 711 nm, and 796 nm, respectively. Great blueshifts were observed for the nanotubes with very thin wall thickness, which are caused by the quantum confinement.[1] (a) Xia, Y.; et al. Adv. Mater. 2003, 15, 353-389. (b) Shen, G. Z.; Chen, D. J. Am. Chem. Soc. 2006, 128, 11762.[2] Shen, G. Z.; et al. Appl. Phys. Lett. 2006, 88, 143105.[3] (a) Shen, G. Z.; et al. Chem. Eur. J. 2006, 12, 2987. (b) Shen, G. Z.; et al. Appl. Phys. Lett. 2006, 88, 243106. (c) Shen, G. Z.; et al. Appl. Phys. Lett. 2006, 88, 123107.[4] Shen, G. Z.; et al. Angew. Chem. Int. Ed. 2006, in press.
5:00 PM - EE2.10/DD3.10
PLD Synthesis of Aligned Fe3O4 and ε-Fe2O3 Nanowires and Nanobelts.
Jenny Morber 1 , Yong Ding 1 , Michael Haluska 1 , Yang Li 2 , J. Liu 2 , Zhong Wang 1 , Robert Snyder 1
1 Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States, 2 Physics, University of Texas at Arlington, Arlington, Texas, United States
Show Abstract5:15 PM - EE2.11/DD3.11
Pulsed-Potential Regimes for the Electrodeposition of Bismuth Telluride Nanowires in Porous Alumina.
Lynn Trahey 1 , Catherine Becker 1 , Jeff Sharp 2 , Angelica Stacy 1
1 Chemistry, University of CA, Berkeley, Berkeley, California, United States, 2 , Marlow Industries, Inc., a Subsidiary of II-VI Incorporated, Dallas, Texas, United States
Show Abstract5:30 PM - EE2.12/DD3.12
Microwave-assisted Rapid Synthesis of Silver Nanowires.
Linfeng Gou 1 , Jeffery Zaleski 1
1 , Indiana University , Bloomington, Indiana, United States
Show AbstractWe report the rapid, microwave-assisted aerobic synthesis of silver nanowires based on the polyol method. Benchtop dissolution of NaCl and AgNO3 in ethylene glycol and subsequent heating using microwave irradiation (300W) in the presence of polyvinylpyrrolidone generates Ag nanowires in ~80% yield in 3.5 minutes. Upon purification, microscopy (TEM, SEM) and powder X-ray diffraction reveal a uniform array of crystalline Ag nanowires 45 nm x 4-12 mm. Wire formation is highly dependent upon the microwave heating power, time, and NaCl:AgNO3 ratio due to the rapid heating process and the presence of O2 as an etching coreagent. The nanowire formation mechanism, particularly the role of microwave irradiation as compared to the traditional heating techniques, will be presented. The microwave assisted preparation does not require any external seed crystals, precursors, or mechanical stirring, and is conducted under ambient O2 conditions, leading to significant potential for the large-scale fabrication of Ag nanowires using this approach. Additionally, the rapid heating feature of microwave can be adapted to many hydrothermal/solvothermal approaches for preparing other 1-D nanostructures. Specific examples of these nanowire materials will be discussed.
5:45 PM - EE2.13/DD3.13
Multicolor Nanolasers from Individual Multi-quantum Well Nanowire Heterostructures.
Fang Qian 1 , Yat Li 1 , Silvija Gradecak 1 , Hong-Gyu Park 1 , Yong Ding 2 , Zhong Lin Wang 2 , Charles Lieber 1
1 Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States, 2 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show Abstract
Symposium Organizers
Wei Zhao University of Arkansas
Pehr E. Pehrsson Naval Research Laboratory
Stephen K. Doorn Los Alamos National Laboratory
Jie Liu Duke University
Phaedon Avouris IBM T. J. Watson Research Center
Symposium Support
Army Research Office
EE3: Functionalization, Charge Transfer and Redox of Nanotubes and Nanowires
Session Chairs
Tuesday AM, April 10, 2007
Room 2016 (Moscone West)
9:00 AM - **EE3.1
Chemistry and Applications of Carbon Nanostructures
Robert Haddon 1
1 , University of California, Riverside, California, United States
Show AbstractI will discuss the role of chemistry in the functionalization and processing of carbon nanostructures for application as sensors, detectors and thermal management materials.
9:30 AM - EE3.2
A Study of Nanotubes Dispersion Mechanism by Gold-Labeled Protein Molecules
Oren Regev 1 , Pola Goldberg 1
1 Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva Israel
Show Abstract Exfoliation of single-wall carbon nanotubes (SWNTs) by an appropriate dispersant plays a key role in fully realizing their possible mechanical, electrical or biomedical applications. Exploring the behavior of nanotube-protein conjugates is extremely relevant to biomedical applications, such as drug delivery, in which they act as bio-carriers. Proteins are found to be readily transported inside various mammalian cells by nanotubes, acting as molecular transporter. However, the few experimental details collected on the dispersion mechanism limit the realization of the full spectrum of potential applications. We study the dispersion mechanism of raw SWNTs by bovine serum albumin (BSA) protein, labeled with colloidal gold nanoparticles. We found that proteins are located close to the SWNTs and the average distance between protein molecules along the SWNT is few tens of nanometers, much longer than earlier assumed. We suggest that upon BSA exposure to the hydrophobic surface of the SWNT, its hydrophilic residues are directed towards aqueous environment while the hydrophobic ones adsorb to the hydrophobic surface of the nanotubes with sequential wrapping around the SWNT. Importing the gold-labeling technique, well-known in immunocytochemistry, but rarely used in studies related to NT dispersion, may provide a different and unique tool to study nanotubes exfoliation systems via proteins, polymers and surfactants. The study is performed using transmission electron microscopy (TEM), cryogenic-TEM (cryo-TEM), atomic force microscopy (AFM) and circular dichroism (CD).
9:45 AM - **EE3.3
Chirality-Resolved Separation and Chemistry of Single Wall Carbon Nanotubes.
Ming Zheng 1
1 , DuPont Central Research and Devleopment, Wilmington, Delaware, United States
Show AbstractThis talk will provide an update on the DNA-based separation of single-wall carbon nanotubes (SWNTs) carried out by us in the past 2-3 years. Experimental advancement on chirality-resolved separation of SWNTs will be presented. We have also found that facile electron-transfer occurs between SWNTs and small-molecule redox reagents in aqueous solution, in a way that strongly dependent on the electronic structure of SWNTs. Possible applications of this chemistry in materials preparation and in energy conversion will be discussed.
10:15 AM - EE3.4
Chirality Dependent Aggregation of Single-Walled Carbon Nanotubes
Sandip Niyogi 1 , Sofiane Boukhalfa 1 , Satishkumar Chikkannanavar 1 , Stephen Doorn 1
1 C-CSE, Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show AbstractSingle-walled carbon nanotubes (SWNT) dispersed in water using sodium dodecylsulfate allows us to study the properties of individual nanotubes. In these dispersions, the van der Waals attractive force between the nanotubes is overcome by the electrostatic repulsion between the dodecylsulfate groups adsorbed on the nanotube surface. Using absorbance and emission spectroscopy, we demonstrate that, by titrating the dispersions with salt solutions, the surface charge on the SWNTs can be neutralized, aggregating SWNTs of particular diameter and chirality. Under such conditions, identical chiralities will aggregate initially which may then form larger heterogeneous mixtures. Our results show that the surface charge density necessary to stabilize SWNTs individually as well as the aggregation number of SDS on SWNTs depend simultaneously on the diameter and chiral angle.
10:30 AM - **EE3.5
Surfactant-templated Assembly of Carbon Nanotube in Multi-functional Nanoconjugates.
Dan Wang 1 , Ru Zhang 2 , Maureen Heines 1 , Liwei Chen 1
1 Chemistry and Biochemistry, Ohio University, Athens, Ohio, United States, 2 Physics and Astronomy, Ohio University, Athens, Ohio, United States
Show Abstract11:00 AM - EE3: Redox
Break
11:15 AM - **EE3.6
Separation and (n,m)-Abundance Evaluation of Single Wall Carbon Nanotubes
Fotios Papadimitrakopoulos 1
1 Institute of Materials Science, University of Connecticut, Storrs, Connecticut, United States
Show AbstractPrecise control of single wall carbon nanotubes (SWNTs) over length, diameter, type (or otherwise termed metallicity (metallic vs. semiconducting)) and chirality are of pivotal importance for their future involvement in high-end electronic and optoelectronic devices as well as in biosensory applications. Until recently, very little was known on how to go about separating met- from sem-SWNTs and the underlying nature of such separation. In this contribution, the various separation methodologies will be discussed along with various characterization methodologies to access separation efficiencies. Attention will be devoted on our recent efforts to successfully reconstruct: (i) the resonance Raman profiles of the radial breathing mode (RBM) of HiPco SWNTs,[1] and (ii) the near infrared absorption of the ES11 absorption spectrum of the narrow diameter nanotubes,[2] towards deciphering (n,m)-abundance in the sem-portion of SWNTs.CITED REFERENCES:[1] Z. Luo, F. Papadimitrakopoulos, S. Doorn, Applied Physics Letters, 2006, 88, 073110.[2] Z. Luo; L. D. Pfefferle; G. Haller; F. Papadimitrakopoulos; J. Am. Chem. Soc. 2006, ASAP.Financial support from AFOSR and ARO is kindly appreciated.
11:45 AM - EE3.7
Using DNA's Molecular Biology Tools for Carbon Nanotube Purification and Assembly
Jennifer Cha 1 , Christine Micheel 1 , Bob Shelby 1 , Donald Bethune 1 , Marcus Freitag 2
1 , IBM Almaden Research Center, San Jose, California, United States, 2 , IBM T.J. Watson, Yorktown Heights, New York, United States
Show AbstractDue to their nanometer sizes and molecular recognition capabilities, biological systems have garnered much attention as vehicles for the directed assembly of nanoscale materials. One of the largest challenges of this research has been to successfully interface biological systems with electronic materials, such as semiconductors and metals. We demonstrate here that long genomic single stranded DNA (>>100 bases) of a completely random sequence of bases can be used to disperse CNTs efficiently through the single stranded DNA's (ssDNA) ability to form tight helices around the CNTs with distinct periodic pitches. While this process occurs irrespective of the DNA sequence, we show that this process is highly dependent on the removal of complementary strands. We also demonstrate that although the helix pitch-to-pitch distances remain constant down the length of a single CNT, the distances can be variable from one DNA-CNT and another. I will discuss our research efforts and discoveries toward using genomic DNA for purification and separation of CNTs.
12:00 PM - **EE3.8
Controlling the Properties of Carbon Nanotubes Through Noncovalent Functionalization with Designed Peptide Systems.
Gregg Dieckmann 1 2 , Eric Becraft 1 , Ray Baughman 1 2 , Alan Dalton 3 , Rockford Draper 1 2 4 , Inga Musselman 1 2 , Paul Pantano 1 2
1 Chemistry Department, The University of Texas at Dallas, Richardson, Texas, United States, 2 The NanoTech Institute, The University of Texas at Dallas, Richardson, Texas, United States, 3 Department of Physics, The University of Surrey, Guildford, Surrey, United Kingdom, 4 Department of Molecular & Cell Biology, The University of Texas at Dallas, Richardson, Texas, United States
Show AbstractWhile carbon nanotubes (CNTs) have exciting properties and numerous potential applications, their inherent hydrophobic nature makes them difficult to purify, manipulate and interface with biological materials. To fully realize the potential utility of CNTs, strategies for the effective dispersion, separation and organization of these materials must be devised. In this presentation, work by the Bionanosciences Group at the University of Texas at Dallas involving the use of designed amphiphilic peptides to achieve these goals will be described, with emphasis placed on the peptide design, as well as the characterization of the resulting peptide/CNT composites. Through a combination of computer modeling and chemical synthetic strategies, we have created small peptide systems with properties tailor-made for optimum interactions with CNTs. To date, our peptides have centered around two basic designs: (1) amphiphilic helical peptides with aromatic-rich apolar surfaces, and (2) closeable cyclic peptides (CCPs)—peptides containing alternating L- and D-amino acids and thiol-derivativized ends for reversible cyclization. One major advantage to the use of synthetic peptides is the rich diversity of functional groups that can be incorporated through the solid-phase synthetic strategy, allowing one to design peptides with a wide range of controlled structures and functions.Results from circular dichroism, Raman, UV/Vis/NIR, SEM, TEM and AFM studies will be discussed which demonstrate that designed amphiphilic peptides are effective at dispersing CNTs in aqueous solution, debundling the CNTs yielding individual CNTs, and organizing them into different macromolecular architectures depending on solution conditions. Furthermore, the CCPs have demonstrated diameter-selective dispersion of HiPco CNTs, providing us with a possible method for preparation of CNT fractions with selected diameter populations. The rich diversity available with designed peptide systems, as well as the ability to control CNT organization by utilizing the self-assembly properties of the peptides, provides a facile and versatile method for the manipulation of CNTs for future applications.
12:30 PM - EE3.9
Ion Exclusion in the Surface-modified Carbon Nanotube Membranes.
Hyung Gyu Park 1 2 , Jason Holt 2 , Greg Klunder 2 , Costas Grigoropoulos 1 , Aleksandr Noy 2 , Olgica Bakajin 2
1 Mechanical Engineering, University of California Berkeley, Berkeley, California, United States, 2 Chemistry, Materials and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California, United States
Show Abstract12:45 PM - EE3.10
Patterned Growth of Organic Semiconducting Single Crystals on Carbon Nanotube Templates.
Shuhong Liu 1 , Alejandro Briseno 1 , Stefan Mannsfeld 1 , Wei You 1 , Jason Locklin 1 , Zhenan Bao 1
1 Chemical Engineering, Stanford University, Stanford, California, United States
Show AbstractSingle-crystal organic field-effect transistors have demonstrated high performance and represented perfect device structures for studying fundamental science associated with charge transport in organic materials. However, it remains a technical challenge to integrate single-crystal devices in practical electronic applications. One of the major impediments is that organic single-crystal devices are commonly fabricated one-by-one by handpicking and thus hard to be mass-produced with high throughput. Moreover, the surface of organic crystals can be damaged by processing techniques such as photolithography. Therefore, there is a great need for a general method for the controlled growth of organic semiconducting single crystals directly onto device structures. In this work, we use patterned carbon-nantube networks as templates to study the selective nucleation and growth of various organic semiconducting single crystals. Carbon nanotubes are selected as the templating materials for the following reasons. First, organic semiconducting molecules and carbon nanotubes might have π-π interactions; Second, carbon nanotubes have been reported to act as conducting rods for shortening channel length and tuning device performance; Third, carbon nanotubes can be easily patterned. In this work, using patterned carbon nanotubes as templates, we have observed that organic single crystals such as pentacene, tetracene, sexiphenylene etc. can be selectively deposited only on the carbon nanotube regions under certain experimental conditions. Using pentacene as a model system, we did a statistic study on the dependence of the number of crystals on the patterning sizes or on the density of carbon nanotubes. A variety of techniques, such as optical microscopy, scanning electron microscopy, atomic force microscopy, and X-ray diffraction etc., are used to observe the crystal nucleation and growth and study the crystal patterning mechanism. Through patterning carbon nanotubes onto a substrate with pre-patterned source-drain electrodes, organic single crystals can be grown selectively in the channel region and large arrays of organic single-crystal transistors are thus fabricated and characterized. The impact of carbon nanotube on the device performance is also discussed.
EE4: Spectroscopic Properties and Medical and Clinical Applications of Nanotubes and Nanowires
Session Chairs
Phaedon Avouris
Stephen Doorn
Wei Zhao
Tuesday PM, April 10, 2007
Room 2016 (Moscone West)
2:30 PM - **EE4.1
On-Wire Lithography
Chad Mirkin 1 , Matthew Banholzer 1
1 , Northwestern University, Evanston, Illinois, United States
Show AbstractTuesday, April 10New Presenter - *EE4.1 @ 1:30 amOn-Wire Lithography. Matthew Banholzer
3:00 PM - EE4.2
The Structure and Transport of Water and Hydrated Ions Within Single Wall Carbon Nanotubes.
Jason Holt 1 , Jason Giuliani 1 , Julie Herberg 1 , Samuel Webb 2 , Apurva Mehta 2
1 Chemistry Materials and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States, 2 , Stanford Synchrotron Radiation Laboratory, Menlo Park, California, United States
Show Abstract3:15 PM - **EE4.3
Near-infrared Fluorescence Studies of Single-Walled Carbon Nanotubes
R. Bruce Weisman 1
1 Department of Chemistry, Rice University, Houston, Texas, United States
Show AbstractThe intrinsic near-IR fluorescence of semiconducting single-walled carbon nanotubes (SWNTs) provides a powerful tool for a variety of basic and applied investigations. Several current studies in this area will be described. In one, near-IR video-microscopy is used to monitor the diffusional motions of SWNTs in ambient aqueous suspensions and to assess the thermally-induced bending deformations of (n,m)-identified nanotubes. Analysis provides values of bending stiffness as a function of SWNT diameter. In another project, the products of E22 peak absorptivities and fluorescence quantum yields are measured on an absolute basis and compared for a range of SWNT diameters, chiral angles, and mod 3 characters. The detailed compositions of bulk samples are found through increasingly sensitive, sophisticated, and automated fluorimetric analysis methods. Bulk fluorescence spectroscopy of aqueous SWNT suspensions reveals species-dependent changes in E11 peak positions, widths, and emission yields as a function of temperature. Finally, the ability of near-IR fluorescence microscopy to detect single SWNTs in biological media is illustrated by in vivo studies. In one, the circulation half-life of nanotubes in the blood stream of rabbits is measured to be 1.0 hours, and nanotubes are found to be taken up by the liver. In another, SWNTs are observed to enter the tissues of drosophila larvae following oral exposure through their food supply. Quantitative tissue biodistributions are deduced from fluorescence microscopy.
3:45 PM - EE4.4
Direct Measurement of the Fluorescence Quantum Yield for Individual Single-Walled Carbon Nanotubes
Todd Krauss 1 , Lisa Carlson 1
1 Chemistry, University of Rochester, Rochester, New York, United States
Show AbstractRecently, the optical properties of single-walled carbon nanotubes (SWNTs) have been the subject of much interest. In particular, SWNTs could be attractive for applications in telecommunications, biological sensing, displays, solar cells, and quantum optics. Still, one factor potentially limiting the development of applications based on SWNT fluorescence has been the absence of an accurate determination of the emissive efficiency of SWNTs. From a fundamental point of view, a molecule’s luminescence efficiency is one of its most important photophysical parameters, one that often influences whether a system incorporating this molecule is selected for development into a given photonics application. For an ensemble of nanotubes, the fluorescence quantum yield (QY) is extremely low, typically less than 0.1%. Given that the QY is so low, it is somewhat surprising that fluorescence from individual nanotubes can be detected with relatively high signal to noise. Indeed, for a single nanotube suspended in air, recent estimates suggest that the single molecule fluorescence QY is almost two orders of magnitude higher than the ensemble value (~7%). It is clear that a direct and accurate measurement of the fluorescence QY for different nanotube structures (i.e. (n,m)) would hold significant fundamental importance and technological relevance.We will present measurements of the fluorescence QY of isolated SWNTs, obtained on the single particle level using confocal microscopy. CoMoCAT SWNTs were initially isolated and suspended in D2O using a sodium cholate surfactant. By dispersing dilute suspensions of isolated SWNTs and CdTe/ZnS quantum dots (QDs) onto a quartz substrate, the fluorescence from individual SWNTs and single QDs were measured simultaneously. Comparisons between the relative fluorescence intensities of the SWNTs and QDs, including simple corrections for the relative absorption cross sections of the two materials, allowed for a direct determination of the SWNT QY given that the QY of single QDs is very well defined. We have found that the single SWNT QY is ~2%, which is almost two orders of magnitude larger than when determined in ensemble measurements and is on the same order as that of suspended individual SWNTs. The significance of our approach is that we used a straightforward relative quantum yield measurement to determine the individual SWNT fluorescence QY, opposed to a very difficult absolute quantum yield measurement for which it is critical to know exactly the amount of excitation received by the sample, and difficult to accurately quantify the exact number of photons received by the detector. We will also report on whether the measured QY represents an intrinsic property of various nanotube structures, (n,m), or if the QY is influenced by other factors such as the local environment, intertube interactions, and defects.
4:00 PM - EE4: Spec
Break
4:15 PM - **EE4.5
Nanorod and Nanowire Optical Properties.
Alexander Efros 1
1 Center for Computational Materials Science, Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractThere is growing interest in nanometer-scale crystalline semiconductor structures of various shapes, such as nanocrystals (NCs), nanorods (NRs), and nanowires (NWs), created using the "from-the-bottom-up" technological approach. The optical properties of NRs and NWs, however, differ significantly from those of NCs. The photoluminescence of NRs and NWs is strongly linearly polarized PL and shows an increase in the global Stokes shift. The size and shape dependence of optical and tunneling gaps measured in CdSe NRs shows an unexpectedly large difference that cannot be explained by the electron-hole Coulomb correction to the optical gap used for NCs. We have shown theoretically that this difference in optical properties is caused by one-dimensional excitons formed in nanorods and nanowires. This theory, which takes into account the anisotropy of spatial and dielectric confinement, describes the size dependence of interband optical transitions, exciton binding energies, and the fine structure of the ground exciton state [1] that controls the PL in CdSe nanorods and nanowires.[1] A. Shabaev and Al. L. Efros, NanoLetters v.4, 1821 (2004).
4:45 PM - EE4.6
The Temperature Dependence of Excitonic Decay in Single-wall Carbon Nanotubes.
Michael Heben 1 , Wyatt Metzger 1 , Timothy McDonald 1 2 , Chaiwat Engtrakul 1 , Jeffrey Blackburn 1 , Gregory Scholes 3 , Garry Rumbles 1
1 Basic Science, National Renewable Energy Lab, Golden, Colorado, United States, 2 Department of Applied Physics, National Renewable Energy Lab, Golden, Colorado, United States, 3 Centre for Quantum Information and Quantum Control, and Institute for Optical Sciences, University of Toronto, Toronto, Ontario, Canada
Show Abstract5:00 PM - **EE4.7
Hollow Gold Nanoshells and Nanotubes: Interesting Optical Properties and SERS applications
Jin Zhang 1 , Adam Schwartzberg 1 2 , Tammy Olson 1 2 , Chad Talley 2
1 Chemistry, UC Santa Cruz, Santa Cruz, California, United States, 2 , LLNL, Livermore, California, United States
Show AbstractNearly monodisperse hollow gold nanoshells (HGNs) with tunable interior and exterior diameter have been synthesized by sacrificial galvanic replacement of cobalt nanoparticles. By carefully controlling particle size and wall thickness, it is possible to tune the peak of the surface plasmon band absorption between 550 nm and 820 nm. Cobalt particle size is tunable by simultaneously changing the concentration of sodium borohydride and sodium citrate, the reducing and capping agent, respectively. The thickness of the gold shell can be varied by carefully controlling the addition of gold salt. With successful demonstration of ensemble as well as single HGN surface enhanced Raman scattering (SERS), these HGNs have shown great potential for chemical and biological sensing applications, especially those requiring nanostructures with near IR absorption. With the assistance of an external magnetic field, the cobalt nanoparticles can be aligned and used to produce Au nanotubes with very uniform diameters. This is potentially useful for using magnetic fields to direct the fabrication of metal nanostructures in a controlled manner for nanoelectronics and nanophotonics applications.
5:30 PM - EE4.8
Absolute potential of the Fermi level of single-walled carbon nanotubes via hydrogenase charge-transfer complex formation
Timothy McDonald 1 2 , Drazenka Svedruzic 1 , Jeffrey Blackburn 1 , Paul King 1 , Michael Heben 1
1 Basic Science, National Renewable Energy Lab, Golden, Colorado, United States, 2 Department of Applied Physics, Columbia Unviersity, New York, New York, United States
Show AbstractSingle-walled carbon nanotubes are interesting candidates in energy conversion devices as active photo-collecting elements, for dissociation of bound excitons and charge-transfer from dyes or quantum dots, or as molecular wires to transport charge. The absolute potential of the Fermi level of nanotubes as a function of nanotube type is not presently understood, which is important for many nanotube applications and sorting strategies. Hydrogenases are enzymes that can efficiently catalyze the production of molecular hydrogen and may serve to inspire new materials for use in biological fuel cells and direct conversion of sunlight into hydrogen. Understanding hydrogenase redox reactions are important; however, study is impeded by the challenge of immobilizing the hydrogenase of interest on electrodes for electrochemical study. Aqueous suspension of SWNTs bound with enzymes and probed by steady-state photoluminescence, absorption, and Raman spectroscopies can provide information such as the enzyme’s electrochemical redox potential, evidence of SWNT-hydrogenase complex formation and the diameter-dependence of absolute potential of the Fermi level of semiconducting SWNTs. In this work, we find a solution-phase reaction between recombinant [FeFe] hydrogenase from Clostridium acetobutylicum and SWNTs suspended in aqueous suspension in which a stable charge-transfer conjugate is formed. The evidence for the charge-transfer lies in the bleach of SWNT photoluminescence (PL) and absorption transitions and changes in the Raman signature of the nanotubes. The electrochemical potential of the hydrogenase is determined by the redox state of its active Fe-S cluster, which is sensitive to the presence of molecular hydrogen. Also, hydrogenase is irreversibly deactivated by molecular oxygen. The electrochemical potential of the hydrogenase can be tuned by changing the composition of the gas in a head space When mixed with sufficient molecular hydrogen, the hydrogenase is in a reduced state, and when no molecular hydrogen is present, it is in an oxidized state, in the absence of other redox species able to interact with the enzyme. The redox potential of the hydrogenase in both the reduced and oxidized state can be probed by looking at which nanotubes’ transitions have been bleached when SWNTs are mixed with the enzyme in each state. We utilize this effect to observe the kinetics of bleaching in SWNT optical transitions due to charge-transfer from the hydrogenase without the diameter-dependent influence of the encapsulating surfactant molecule. This provides a method to determine the absolute potential of the Fermi level of the isolated semiconducting SWNTs. In addition, the hybrids may find application in energy conversion applications. The nanotubes in this complex may function as a “molecular wire” to couple the active enzyme to light-harvesting species.
5:45 PM - EE4.9
Single-walled Carbon Nanotube Scaffolds Promote Stem Cell Differentiation into Bone Forming Cells.
Xiaomin Tu 1 , Charles Skinner 2 , Xiao-Dong Chen 2 , Wei Zhao 1
1 Department of Chemistry, University of Arkansas, Little Rock, Arkansas, United States, 2 Division of Endocrinology and Metabolism, Center for Osteoporosis and Metabolic Bone Diseases, Department of Internal Medicine, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, Arkansas, United States
Show AbstractThe use of carbon nanotubes for tissue engineering has become one of the most fascinating applications. The exquisite electronic and mechanical properties of carbon nanotubes may provide a three-dimensional (3D) microenvironment that closely mimics in vivo situation for facilitating the use of stem cells in the tissue regeneration. Therefore, it is important to know whether carbon nanotubes enhance the adhesion, proliferation, and differentiation of stem cells. Here, we hypothesized that the carbon nanotubes promote the differentiation of osteoblast progenitors into mature osteoblasts. To test this hypothesis, we quantified the differentiation of murine osteoblast progenitors, with and without pro-differentiating growth factor Bone Morphogenetic Protein-2 (BMP-2), cultured on the 3D scaffolds made by single-walled carbon nanotubes (SWNTs). Three types of SWNT samples, chitosan functionalized SWNTs, acid-oxidized SWNTs, and surfactant-free pristine SWNTs were used for the construction of these 3D microarchitectures. Osteoblast progenitors were harvested from calvariae from 3~5-day-old mice, and cultured on the 3D scaffolds made by carbon naotubes until ~ 80% confluent. Then the cells were treated with BMP-2 (100 ng/ml) for 5 days. It was found that osteoblast progenitors cultured on the SWNTs dramatically increased the level of mature osteoblastic marker osteocalcin in either the absence or the presence of BMP-2, as compared to the cells cultured on the regulate tissue culture plastic plates. The results suggested that SWNTs highly promote osteoblast progenitor differentiation into mature osteoblasts. The finding indicates that SWNTs may provide an ideal scaffold for facilitating the differentiation of osteoblast progenitors in the repair of bone defects.
EE5: Poster Session: Synthesis
Session Chairs
Phaedon Avouris
Stephen Doorn
Jie Liu
Pehr Pehrsson
Wei Zhao
Wednesday AM, April 11, 2007
Salon Level (Marriott)
9:00 PM - EE5.1
Growth of Single Wall Carbon Nanotubes Investigated by In-situ Mass Spectroscopy.
SeongMin Kim 1 , Kenneth B.K. Teo 1 , Aun Shih Teh 1 , Yan Zhang 1 , Martin Bell 1 , Mark Mann 1 , Bill Milne 1 , Seungbek Lee 2
1 Engineering, University of Cambridge, Cambridge United Kingdom, 2 Division of Electronics and Computer Engineering, Hanyang University, Seoul Korea (the Republic of)
Show Abstract9:00 PM - EE5.10
Direct Growth of Multi-walled Carbon Nanotubes on Sharp Tips for Electron Microscopy
Mark Mann 1 , Ken Teo 1 , Bill Milne 1
1 Engineering, Cambridge University, Cambridge , Cambridgeshire, United Kingdom
Show AbstractThe favorable electron optical properties of carbon nanotubes (CNTs) have been studied in detail,but the application to electron sources has been limited by the complexity of the fabricationprocess. CNTs offer low-extraction voltage, high brightnesssolutions to electron microscopy demands, but thechallenge has been to develop a repeatable and reliable process to bring CNT electron source devices to market. Electron source manufactures are unlikely to investin CNT electron sources until a simplification ofthe process to position high-quality nanotubes ontotungsten tips is developed and proven to work sothat the production of such tips can be scaled up tomass production. We describe three significantchallenges that have been overcome. In orderfor electron beam equipment to work effectively,there must be only a single source of electrons,hence a single CNT. As CNTs grow from a catalystparticle, the first challenge is to place a singlecatalyst particle at the vertex of the tip by the simplestand most reproducible process possible. Thesecond challenge is to ensure that the nanotube isaligned in-axis with the rest of the tungsten tip.The third challenge is to improve the quality ofthe nanotube formed at the top of the tip. Thiscan be achieved by thermally annealing the CNTs following deposition. We report the use of Plasma Enhanced Chemical Vapor Deposition (PECVD) as a means to reliably deposit multi-walled CNTs directly onto the apex of sharply etched tungsten tips, alignedto the vertical axis of the tips. The tip is millimeters long, but thistechnique allows for the accurate positioning of singleCNTs without the use of lithography for use aselectron sources. We show that these emitters have excellent stability (<1%) and reduced brightnesses with values up to three times that of comparable Schottky sources. This fabrication method is scalable to mass production.
9:00 PM - EE5.11
Multi-Wall Carbon Nanotube Synthesis, Characterization, and Utilization.
Roberta DiLeo 1 , Brian Landi 1 , Seth Hubbard 1 , Ryne Raffaelle 1
1 Physics, Rochester Institute of Technology, Rochester, New York, United States
Show AbstractMulti-walled carbon nanotubes (MWNT), much like their single wall cousins, are being evaluated for a large number of potential technological applications. The development of these various applications may well depend on the efficient synthesis of high quality materials and the concomitant methods by which their quality is assessed. The synthesis and characterization of MWNTs produced by injection chemical vapor deposition (CVD) has been investigated. A series of reactions using a 0.08 M concentration of cyclopentadienyliron dicarbonyl dimer in toluene was completed with variation of experimental parameters: temperature ranged from 600-900 °C, gas flow rates between 0.5-2.5 L/min, and precursor injection rates at 1.5 – 4.5 mL/hr. The as-produced material was characterized using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Raman spectroscopy. Carbonaceous purity assessment for as-produced MWNTs using Raman spectroscopy was investigated. Raman spectroscopy was performed on a reference sample set containing pre-determined ratios of MWNTs and representative synthesis by-products. Changes in the characteristic Raman peak ratios (i.e. ID/IG, IG’/IG, and IG’/ID) as a function of MWNT content were measured. Calibration curves were generated from the reference samples and used to evaluate MWNTs synthesized under the different conditions shown above. The efficacy of using Raman spectroscopy in conjunction with thermogravimetric analysis for quantitative MWNT purity assessment, the use of this synthesis technique to produce high quality MWNTs, and potential applications for these materials will be discussed.
9:00 PM - EE5.12
Investigation on Site Density of Carbon Nanotube Forests
Zhengchun Liu 1 , Sang-Hwui Lee 1 , Navdeep Bajwa 2 , Lijie Ci 2 , Swastik Kar 2 , Pulickel Ajayan 2 , James Lu 1
1 Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, New York, United States, 2 Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States
Show AbstractAbstract:Carbon nanotube (CNT) forests, which are made of a great number of vertically-aligned CNTs, are promising materials for various applications such as IC interconnects, heat-sinks, and field emission materials. Site density is an important parameter to describe how dense a CNT forest is. For applications such as CNT interconnects and heat-sinks, the higher the site density, the more the conduction channels, the higher the performance. In this work, we developed a quantitative method to measure site densities of CNT forests. Vertically-aligned CNTs are fixed in a polymer matrix, i.e., BenzoCycloButene (BCB). After mechanical polishing and selective polymer etching, CNT ends are exposed for SEM observations. The site density of vertically aligned multi-wall CNTs is obtained through counting CNT ends in SEM images with image analysis software. We found that multi-wall CNTs, which were grown with two different CVD processes—ferrocene/xylene process and Fe-Al/ethylene process, have site densities ~10 tubes/um^2 and ~53 tubes/um^2, respectively. The statistical distribution of CNT site density across the growth surface is also investigated.
9:00 PM - EE5.14
Combined Experimental and Theoretical Investigation on Synthesis of Massively Aligned Single-Walled Carbon Nanotubes
Koungmin Ryu 1 , Alexander Badmaev 1 , Xiaolei Liu 1 , Bo Lei 1 , Lewis Arco 1 , Chongwu Zhou 1
1 Electrical Engineering, Univ. of Southern California, Los Angeles, California, United States
Show AbstractSynthesis of highly aligned single-walled carbon nanotubes with controlled diameters is an important step towards manufacturable ultra dense carbon nanotube integrated circuits. We have successfully demonstrated the synthesis of highly aligned carbon nanotube arrays on a-plane sapphire and miscut quartz substrates. Our calculation of the Lennard-Jones potential clearly reveals that a nanotube would lie normal to the c-axis of a-plane sapphire for minimized potential energy, consistent with our experimental observation. In addition, in-depth study has been carried out on the diameter dependence of the alignment between the nanotubes. We found that the best degree of alignment was achieved for nanotubes of optimized diameter, while larger nanotubes displayed less alignment. This subtle effect was also confirmed by our numerical simulation based on the van der Waals interaction between nanotubes and substrates. Furthermore, we have developed a patterned growth method to control both the orientation and position of the aligned nanotubes. This was achieved by using photolithography to deposit catalyst at desired locations on sapphire or quartz, followed by CVD growth of the aligned nanotubes. Our work paves the way for a better understanding of the aligned synthesis and could eventually lead to the growth of aligned nanotubes with controlled diameters and even chiralities.
9:00 PM - EE5.15
Growth of Aligned Carbon Nanotube Films with Self-Assembled Conical Tips by Control of Catalyst Preparation
Mineo Hiramatsu 1 , Masaru Hori 2
1 Department of Electrical and Electronic Engineering, Meijo University, Nagoya Japan, 2 Department of Electrical Engineering and Computer Science, Nagoya University, Nagoya Japan
Show AbstractCarbon nanotubes (CNTs) have attracted much attention for several applications, such as electron field emitter arrays and multi-level interconnection of ultra-large scale next generation integrated circuits. It is well known that metallic catalysts such as Fe, Co, Ni are essential to the nanotube nucleation on the substrate. And it is very important for the nanotube growth to prepare small catalytic particles on the substrate. In this work, catalytic nanoparticles were prepared on the Si substrate without buffer layer, using the pulsed arc plasma deposition with alternate use of Co and Ti electrodes. Ti nanoparticles, by mixing with Co nanoparticles, would prevent the formation of Co-silicides in the process of substrate heating, and enable to keep the size of Co nanoparticles at approximately 1-2 nm. The synthesis of dense, aligned CNTs on Si substrate was achieved using microwave plasma-enhanced chemical vapor deposition. A mixture of CH4 and H2 was used as a source gas. The flow rates of CH4 and H2 were 50 and 70 sccm, respectively. The microwave power and total pressure were kept at 900 W and 70 Torr, respectively. By the control of catalyst preparation, fabrication of aligned single-walled carbon nanotube (SWNT) film and double-walled carbon nanotube (DWNT) film was controllable. In addition, catalytic nanoparticles were patterned by using a lift-off method, and area-selective growth of vertical SWNTs and DWNTs to form organized CNT microstructures was demonstrated. Furthermore, by tuning the number of cumulative Co nanoparticles, aligned CNT films with self-assembled conical tips on the top were fabricated. The interval and height of conical tips were approximately 800 nm and 1 μm, respectively. As the growth period increased, CNT film thickness increased linearly up to 10 min of growth, while the morphology of the top of CNT film was not changed, suggesting that the structure of self-assembled conical tips was formed in the early stage of growth and our process could be explained by the base-growth mechanism. These self-assembled conical tip structure would be attributed to the appropriate space to swing and the van der Waals force of SWNT or DWNT at the initial stage of CNT growth. Field emission properties for the CNT films with self-assembled conical tips were measured. Threshold field strength was 0.8 and 1.0 V/μm for SWNT and DWNT films with self-assembled conical tips, respectively. This structure would be useful for the field emission application.
9:00 PM - EE5.17
Single-walled Nanotube / Silica Composites through High-pressure Techniques.
Monica Jung de Andrade 1 2 , Marcio Dias Lima 1 2 , Carlos Perez Bergmann 2 , Naira Balzaretti 3 , Tania Costa 4 , Marcia Gallas 3
1 Von Klitzing, Max-Planck Institute for Solid State Research, Stuttgart Germany, 2 Materials Engineering, Federal University of Rio Grande do Sul, Porto Alegre Brazil, 3 Institute of Physics, Federal University of Rio Grande do Sul, Porto Alegre Brazil, 4 Institute of Chemistry, Federal University of Rio Grande do Sul, Porto Alegre Brazil
Show Abstract9:00 PM - EE5.18
Electric Field Assisted Synthesis ofNanostructured metallic Architecture over Carbon Nanotubes
Sundara Ramaprabhu 1 , M. Krishnakumar 1
1 , Indian Institute of Technology, Chennai India
Show Abstract9:00 PM - EE5.19
Low Temperature Growth and Application of Zinc Oxide Nanowires using Zinc Oxide Seeds.
Lee Sunyoung 1 , Hey Jin Myoung 1 , Sunglyul Maeng 1 , Sang Hyeob Kim 1
1 , ETRI, Daejeon Korea (the Republic of)
Show Abstract9:00 PM - EE5.2
Synthesis of Controllably Grown Carbon Nanotubes Interconnects.
Seon Woo Lee 1 , David Katz 1 , Haim Grebel 1 , Avi Kornblit 2 , Daniel Lopez 2
1 Electrical Engineering, New Jersey Institute of Technology, Newark, New Jersey, United States, 2 New Jersey Nanotechnology Consortium (NJNC), Lucent Technologies Bell Labs, Murray Hill, New Jersey, United States
Show AbstractWith single-electron optoelectronic devices in mind, interconnecting metal electrodes by carbon nanotube (CNT) on pre-existing positions is a great challenge. Most fabrication methods so far, are based on dispersing of the CNT on a substrate followed by post-processing contacts. Growth between periodic contacts and between pre-determined pads were also attempted with a limited yield. Here, we demonstrate CNT interconnects between pre-fabricated and addressable two sharp metal catalytic tips, taking advantages of the tips as catalytic lead points. We also take advantage of the tip resolution and the distribution of processing heat over the electrode to grow bridges between precise locations. The metal electrodes were fabricated by optical lithography on oxide covered Si substrate. The catalytic cobalt layer (~30 nm) was deposited on top of a Ti adhesion layer (~30 nm). CNT interconnects were achieved by several methods: CO Plasma Enhanced Chemical Vapor Deposition (PECVD), ethanol CVD and pyrolytic CO CVD. CO PECVD has been used with CO/H2 mixture at a relatively low temperature. Its yield was relatively low though and the quality of CNT interconnect was not to par. Ethanol CVD resulted in many more multi-wall carbon nanotube (MWCNT) than single-wall carbon nanotube (SWCNT) interconnects. CO CVD was the most effective and simplest way to grow CNT interconnects among the three methods, yielding well-aligned and straight SWCNT bridges. Following each process, each CNT interconnect was characterized electrically: by current vs voltage (I-V) and current vs gate potential (I-VG); optically: by Raman spectroscopy, and inspected by use of Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). In short, we demonstrated the fabrication of well-aligned CNT interconnect between pre-determined and addressable electrodes at a yield of 30%. A limited control over the type of the CNT bridge grown, MWCNT or SWCNT, has been also shown.
9:00 PM - EE5.20
Doping of Al-catalyzed Vapor-liquid-solid Grown Si Nnanowires.
Sung Jin Whang 1 , Sung Joo Lee 1 , Wei Feng Yang 1 , Hai Chen Zhu 1 , Han Lu Gu 1 , Byung Jin Cho 1 , Yun Fook Liew 2 1
1 ECE, National University of Singapore, Singapore, Singapore, Singapore, 2 , Data Storage Institute, Singapore, Singapore, Singapore
Show Abstract9:00 PM - EE5.21
Heterogeneous Catalysis of GaN Nanowires: Growth, Structure and Chemistry using In-Situ Transmission Electron Microscopy
Mitra Taheri 1 , Blake Simpkins 2 , Nigel Browning 1
1 Chemistry, Materials and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California, United States, 2 Surface Chemistry Division, US Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractGaN nanowires are a vital building block in various nanoscale optoelectronic devices, such as blue light-emitting diodes and short-wavelength ultraviolet nanolasers. A wire’s electronic properties can be negatively impacted by grain boundaries, extended defects and impurity incorporation that arise during the heterogeneous catalysis process. To understand the specific effects of microstructure and composition on these electrical characteristics, a clear understanding of the structural evolution as a function of catalyst must be obtained. Electron diffraction studies of nanowires grown using CVD showed that those grown using a foreign metal catalyst possessed different textures, or growth orientations, than that of self catalyzed (using GaNO3) wires. Energy Dispersive Spectroscopy and Z-contrast imaging also indicated the presence of catalyst not only at the catalyst ‘bulb’ site, but at the wire-substrate interface as well as along the wire. Specifically, when using NiFe as a catalyst, Fe was found in the both the wire and the catalyst regions, while Ni was confined solely to the catalyst site.To understand the role that catalyst diffusion in a wire plays in the development of a wire’s texture and morphology, GaN nanowires were grown in-situ in a Transmission Electron Microscope using in-situ annealing. Wire structure and chemistry were examined during various stages of growth. Detailed Electron Energy Loss Spectroscopy was performed to examine impurity incorporation during heterogeneous catalysis. Trends in impurity incorporation with morphology and defect concentration were compared for NiFe and Ni catalyst types, and to self catalyzed GaN nanowires.
9:00 PM - EE5.22
Sonoelectrochemical Synthesis of Crystalline Semiconducting Copper Sulfide Nanorods.
Krishna Singh 1 , Mihri Ozkan 2 , Alfredo Martinez 2 , Senthil Gt 2 , Krassimir Bozhilov 3
1 Chemical Engineering, UC Riverside, Riverside, California, United States, 2 Electrical Engineering, UC Riverside, Riverside, California, United States, 3 Earth Sciences, UC Riverside, Riverside, California, United States
Show Abstract9:00 PM - EE5.23
In situ Gas Phase Nanoparticle Seed - Nanowire Integration.
Chad Barry 1 , Jesse Cole 1 , Heiko Jacobs 1
1 Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota, United States
Show AbstractWe report on an in situ gas-phase process to synthesize and integrate seed particles and inorganic nanowires in addressable locations on a surface. The process flow begins with the gas-phase synthesis of nanoparticle seeds. The seed particles are deposited into addressable locations using a fringing field directed assembly process. The fringing field directed assembly process makes use of electrostatic fields that form around conventional resist patterns (PMMA and SiO2) with openings to various substrates to direct the assembly of seed particles into the openings with 50 nm lateral resolution. The seed particles are deposited and grown into nanowires in situ in a second reactor. This process could be used for future integration of functional nanowire devices on heterogeneous systems.
9:00 PM - EE5.24
Growth of Cadmium Telluride Nanowires via Electrodeposition on Gold in AAO Templates.
Subarna Banerjee 1 , Matthew Taylor 1 , Glenn Sklar 2 , Matthew Savage 1 , Jeffrey LaCombe 1
1 Chemical & Metallurgical Engineering, University of Nevada, Reno, Reno, Nevada, United States, 2 , Xtalic Corporation, Medford, Massachusetts, United States
Show Abstract9:00 PM - EE5.25
Controlled Growth of ZnO/TiO2 Nanocables by Using Atomic Layer Deposition
Jae Kwon Hwang 1 , Myung Mo Sung 1
1 Chemistry, Hanyang University, Seoul Korea (the Republic of)
Show AbstractWe have been studied the fabrication of nanocables by using atomic layer deposition (ALD) with a nanoporous membrane as a template. The TiO2 nanotubes were formed inside the polycarbonate (PC) template or anodic aluminum oxide (AAO) by using atomic layer deposition (ALD) from Titanium isopropoxide (TIP) and H2O. Due to the excellent coatings of the ALD process, the wall thickness of the oxide nanotubes and thus the inner diameter of the tubes could be controlled. ZnO deposited with Diethyl Zinc (DEZn) and water inside TiO2 nanotubes. The ZnO/TiO2 nanocables have been investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
9:00 PM - EE5.26
Hierarchical Heterostructures based on 1-D Semiconductor Nanostructures.
Guozhen Shen 1 , Yoshio Bando 1 , Dmitri Golberg 1
1 Nanoscale Materials Center, National Institute for Materials Science, Tsukuba Japan
Show Abstract9:00 PM - EE5.27
Ultralong Aligned ZnS/SiO2 Core-Shell Nanowires.
Daniel Moore 1 , Jenny Morber 1 , Robert Snyder 1 , Zhong Wang 1
1 Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractZnS, a member of the wurtzite family, is a direct wide band gap (3.91 eV) semiconductor, and one of the most important materials in photonics. ZnS is also an important phosphor host lattice material used in electroluminescent devices (ELD), due to its large band gap, which enables emission of visible light without absorption, and efficient transport of high energy electrons. Furthermore, single ZnS nanobelts have been shown to facilitate optically pumped lasing. One dimensional nanostructures such as nanowires have been suggested as ideal candidates for many such electrical and optical applications, and several groups have reported successful synthesis in recent years. However, the extensive reports of one-dimensional nanostructure growth have revealed several challenges that remain. One of these challenges arises from difficulty in producing very long nanowires that can be practically integrated and manipulated post-synthesis through simple methods. Another challenge is the need to synthesize such long nanostructures in ordered or aligned patterns, and in high densities, further augmenting ease of use and scalable applicability. Meeting both of these challenges would move the development of one-dimensional nanostructures a long way towards their industrial application. In this paper, we report the large scale synthesis of laterally aligned, ultralong ZnS nanowires with a SiO2 shell. The ZnS/SiO2 structure is desirable in many applications, because of the silica shell’s ability to shield the wurtzite ZnS nanostructure from damage and to suppress the surface chemical reactivity of the different facets of the nanostructure. Systematic manipulation of experimental parameters provides some information regarding synthesis dynamics, while TEM, XRD and PL studies reveal how structural changes relate to the optical properties of these materials.
9:00 PM - EE5.28
Nanostructured Boron Nitride Films by Chemical Vapor Deposition with Catalyst Fe2O3 and NiO.
Jose Nocua 1 , Olga Medina 1 , Gerardo Morell 1
1 Departmet of physic, University of Puerto Rico, Rio Piedras, Puerto Rico, United States
Show Abstract9:00 PM - EE5.29
Synthesis of Boron Nitride Nanotubes (BNNTs) from a Single Source Precursor on a Metal Deposited Porous Alumina
Ching-Wen Hsieh 1 , Susanta Mohapatra 2 , Indu Mishra 3 , Mano Misra 4
1 Chem/Met Engr., University of Nevada Reno, Reno, Nevada, United States, 2 Chem/Met Engr., University of Nevada Reno, Reno, Nevada, United States, 3 Chem/Met Engr., University of Nevada Reno, Reno, Nevada, United States, 4 Chem/Met. Engr., University of Nevada Reno, Reno, Nevada, United States
Show Abstract9:00 PM - EE5.3
Synthesis of Magnetic Coating on Carbon–Based Nanopaper Sheets by Electrochemical Deposition.
Jan Gou 1 , Roy Blanco 1 , Hao Xing 2 , Li Sun 2 , Gangbing Song 2 , Shih-Hsin Chang 3 , Yaowu Hao 3
1 Department of Mechanical Engineering, University of South Alabama, Mobile, Alabama, United States, 2 Mechanical Engineering, University of Houston, Houston, Texas, United States, 3 Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, Texas, United States
Show Abstract9:00 PM - EE5.30
Si Whisker Growth by Hydrogen Radical using Hot Filament CVD Reactor
Hiroshi Nagayoshi 1 , Nobuo Matsumoto 2 , Suzuka Nishimura 2 , Kazutaka Terashima 2
1 , Tokyo National College of Technology, Tokyo Japan, 2 , Shonan Institute of Technology, Fujisawa, Kanagawa, Japan
Show AbstractThis paper describes the growth mechanism of silicon whisker on a silicon substrate using hot filament CVD reactor. Only hydrogen gas is used as source gas. The particle layer could be obtained at high filament current condition under hydrogen ambient. XPS analysis result suggests that the particle is composed of tungsten silicide. The deposition condition of the particle layer is much depended on the substrate size, surface condition and the distance between the substrate and the filament. The experimental results suggested that the silicon hydride, which generated at the silicon surface by hydrogen radical etching, react with the tungsten filament material around the filament surface, depositing on the silicon substrate. The silicon surface is etched by hydrogen radical and its resultant surface morphology is much depended on the particle deposition pattern. Many silicon whiskers, which diameter is varied from 10 to 30nm, were observed on the textured silicon surface when the source gas flow rate is low. Each whisker has a silicon particle on the tip. The silicon hydride generated by the hydrogen radical etching is much absorbed to the silicide particle when the source gas flow rate is low and that enables the silicon whisker growth from the particle. It is interesting the whisker is stable under hydrogen radical atmosphere. This means that nm size whisker structure is much stable compare to the bulk silicon against etching reaction.
9:00 PM - EE5.31
Isotopic Boron 10 Nitride Nanotubes as Radiation Shielding Materials.
Ying Chen 1 , Jun Yu 1 , Robert Elliman 1 , Dehong Yu 2
1 Electronic Materials Engineering, The Australian National University, Canberra, Australian Capital Territory, Australia, 2 Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Height, New South Wales, Australia
Show Abstract9:00 PM - EE5.32
Several Forms of GaN Nanowires Grown by Ni Catalyst and their Growth Mechanism.
Gary Harris 1 , M. He 1 , J. Halpern 1 , J. Mitchell 1 , R. Vispute 3
1 HNF, Howard University , Washington, District of Columbia, United States, 3 , Bluewave Semiconductor, Columbia , Maryland, United States
Show Abstract9:00 PM - EE5.33
Patterned Metal Nanowire from Nanolithographically Modified Templates and Microwave Filters
Feng Li 1 , Minghui Yu 2 , Mo Zhu 2 , Weilie Zhou 2 , Leonard Spinu 2 , John B. Wiley 1
1 Department of Chemistry and Advanced Materials Research Institute, University of New Orleans, New Orleans, Louisiana, United States, 2 Advanced Materials Institute, University of New Orleans, New Orleans, Louisiana, United States
Show Abstract9:00 PM - EE5.34
Carbon Nanotubes From Charcoal By High Energy Planetary Ball Milling Using Novel Hydride Catalysts.
Sundara Ramaprabhu 1 , M. Krishnakumar 1 , Vimal Thomas 1
1 , IITM, Chennai India
Show Abstract9:00 PM - EE5.4
Fabrication and Characterization of Carbon Nanotube Tip Modified by Focused Ion Beam.
Young-Hyun Shin 1 , Yeo-Hwan Yoon 1 , Eung-Sug Lee 1 , Chang-Soo Han 1
1 Nano-Mechanical Systems Research Center, Korea Institute of Machinery & Materials, Daejeon Korea (the Republic of)
Show Abstract9:00 PM - EE5.5
Controlled Growth of Single-walled and Double-walled Carbon Nanotubes using Catalytic Vapor Phase Growth Method.
SeungChul Lyu 1 , WanSik Hong 1 , Kyungwan Park 1 , Junghyun Sok 1
1 nanotechnology, University of Seoul, Seoul Korea (the Republic of)
Show Abstract9:00 PM - EE5.6
Synthesis of Carbon Nanotubes from Ethanol Using Fe, Co, and Ni Catalysts.
Kazunori Kakehi 1 , Suguru Noda 1 , Shigeo Maruyama 2 , Yukio Yamaguchi 1
1 Department of Chemical System Engineering, the University of Tokyo, Tokyo Japan, 2 Department of Mechanical Engineering, the University of Tokyo, Tokyo Japan
Show AbstractSingle-walled carbon nanotubes (SWNTs) have attracted much attention as promising materials for application in nanodevices due to their unique properties. To realize such applications, their controlled growth on various substrates is crucial. SWNT growth is largely dependent on both catalyst conditions (element of catalyst, diameter, etc.) and reaction conditions (source of carbon, temperature, pressure, etc.). Effects of these conditions interact with each other complicatedly.Previously, we prepared a thickness profile of Co on a SiO2/Si substrate [1] and that of Ni on quartz glass substrate [2] by our ‘combinatorial masked deposition (CMD)’ method [3], carried out alcohol catalytic CVD (ACCVD) [4], and grew SWNTs by metal nanoparticle catalysts spontaneously forming from nominal submonolayers of metal. The thickness profiles formed by this method enable preparation of a series of nanoparticles of various sizes and areal densities on one substrate. Thus we can investigate influence of reaction and catalyst conditions.We prepared thickness profile (about 0.06-3.5 nm) of Fe, Co, and Ni by using CMD method and ACCVD was carried out at 873-1123K. Fe nanoparticles hardly catalyzed the growth of CNTs, however, Co and Ni nanoparticles did. In the case of Co, two active regions appeared with a inactive region in between. Thinner CNTs including SWNTs grew at a thin Co region (~ 0.1 nm), few CNTs grew at a medium region (~ 0.4 nm), and multi-walled carbon nanotubes grew at a thick region (~ 1.5 nm). On the other hand, only one active region appeared for the case of Ni. Ni mainly grew SWNTs at a thin Ni region (~ 0.2 nm), while Ni grew few CNTs at the thicker region. In both Co and Ni catalyst, the active regions shifted to larger metal thickness as increasing growth temperature. We will discuss the underlying mechanisms for these phenomena.[1] S. Noda, et al., Appl. Phys. Lett. 86, 173106 (2005).[2] K. Kakehi, et al., Chem. Phys. Lett. 428, 381 (2006).[3] S. Noda, et al., Appl. Surf. Sci. 225, 372 (2004).[4] S. Maruyama, et al., Chem. Phys. Lett. 360, 229 (2002).
9:00 PM - EE5.7
Understanding the Role of Metal Catalysts in the Nucleation of Carbon Nanotubes.
Santiago Esconjauregui 1 2 , Caroline M. Whelan 1 , Philippe Vereecken 1 , Guido Groeseneken 1 2 , Karen Maex 1 2
1 , IMEC, B-3001 Leuven Belgium, 2 Department of Electrical Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 10, B-3001 Leuven Belgium
Show Abstract9:00 PM - EE5.8
QCM Platforms for Carbon Nanotube Inspection.
Stephanie Hooker 1 , Ryan Schilt 2 1 , Aparna Kar 3 1
1 Materials Reliability, NIST, Boulder, Colorado, United States, 2 , University of Colorado, Boulder, Colorado, United States, 3 , Rensselaer Polytechnic Institute, Troy, New York, United States
Show AbstractCarbon nanotubes continue to emerge as key materials for nanoelectronics, nanodiagnostics, and future drug delivery platforms. Application development in these areas has progressed rapidly over the past few years, prompting renewed concern regarding material quality, particularly given the small amount of high-performance material needed for these products. Consistency from batch to batch is also critical, allowing development of “standard” device fabrication routes. To ensure consistency, quality control methods are needed, a difficult issue given that most analysis techniques used to evaluate nanotube materials sample inappropriate specimen volumes. For example, thermal stability (as determined by thermogravimetric analysis, or TGA) is an excellent indicator of chemical composition, specifically the concentration of metallic impurities present in the material. However, conventional TGA instruments require several milligrams for proper measurement, thereby providing only an average analysis. In contrast, TEM examines an extremely small fraction of the nanotubes present, requiring considerable researcher time to properly analyze a representative distribution of material. In this work, we present an alternative measurement approach for rapid inspection of as-received materials. Quartz crystal microbalance (QCM) devices are used as a low-volume alternative to conventional TGA analysis. Spin coating, dip coating, and spray deposition are used to apply thin nanotube films to the quartz crystal surfaces, which are then heated to three key temperatures of interest along the thermal decomposition curve. Shifts in the crystal’s resonant frequency during heating are directly correlated with changes in specimen mass, allowing one to compare the percentage of mass lost with temperature (i.e., thermal stability) from specimen to specimen. Because the measurements require little time or material to perform, statistical homogeneity within a given batch of nanotubes can quickly be determined, as well as variability between different lots. This paper will demonstrate how this measurement method can be used to elucidate differences between several batches of raw and purified nanotubes produced by a single commercial vendor. Results indicate that even small variations in metallic and amorphous carbon content (both of which can lead to reduced performance) can be readily detected using this new measurement method.
EE6: Poster Session: Nanotubes and Nanowires: Functionalization, Charge Transfer, and Redox
Session Chairs
Phaedon Avouris
Stephen Doorn
Jie Liu
Pehr Pehrsson
Wei Zhao
Wednesday AM, April 11, 2007
Salon Level (Marriott)
9:00 PM - EE6.1
Germanium Nanowires: Synthesis, Characterization and Applications.
Tong Wang 1 , Lauren Klein 1 , Eric Garfunkel 1
1 , Rutgers University, Piscataway, New Jersey, United States
Show AbstractWe report on the structure, chemistry and properties of germanium nanowires grown via vapor-liquid-solid methods in a hot-wall chemical vapor deposition reactor. The diameter, density, and length of the nanowires are regulated by growth conditions (T, P, t, and Au nanoparticle size and density). Directional growth is controlled using epitaxy on single-crystal Si and Ge, aided by appropriate etch chemistries. In order to prevent re-oxidation of the nanowires after removal of the unstable native oxide, we investigated various chemical passivation methods, including chlorination, H-termination, and thiol and alkene passivation. These chemistries are also used to facilitate further surface functionalization and ohmic contact formation and to improve device electrical performance. Another more robust passivation approach is to form stable oxides; we have explored the atomic layer deposition of high-k dielectric materials such as HfO2. These materials are being used as the dielectric in highly scaled nanowire transistors. The nanowires and their coatings have been characterized by scanning and transmission electron microscopies, x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, Rutherford backscattering spectrometry, and Fourier transform infrared spectroscopy. Ge nanowires were also grown on a variety of other substrates for applications including single nanowire field effect transistors, solar cells, sensors, and multi-nanowire thin-film-transistors. The fabrication and properties of these devices are reported.
9:00 PM - EE6.10
Organic Functionalization of Water Soluble Single Walled Carbon Nanotubes.
Seonghwa Ju 1 , Yeong-ri Jung 1 , Sung-Jin Kim 1
1 Nanoscience, Ewha Womans University, Seoul Korea (the Republic of)
Show Abstract9:00 PM - EE6.11
Electrochemical Analysis of Functionalized Carbon Nanotube and Ferritin Complex.
Ji Won Lee 1 , Gordon Wallace 2 , Geoffery Spinks 2 , Kwang Min Shin 1 , Seon Jeong Kim 1
1 Center for Bio-Artificial Muscle and Department of Biomedical Engineering, Hanyang University, Seoul Korea (the Republic of), 2 Intelligent Polymer Research Institute, University of Wollongong, Wollongong, New South Wales, Australia
Show Abstract9:00 PM - EE6.12
Silica Nanotubes for Enzyme Immobilization
Sonal Padalkar 1 , Lia Stanciu 1 2
1 School of Materials Engineering, Purdue University, West Lafayette, Indiana, United States, 2 Department of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States
Show Abstract9:00 PM - EE6.13
Behavior of Different Assemblies of Carbon Nanotube in Chitosan and DNA Solutions with Porphyrins.
Hao Jiang 1 , Weijie Su 1 , Augustine Urbas 1
1 MLPJ, AFRL, WPafb, Ohio, United States
Show Abstract9:00 PM - EE6.14
Functionalized DNA for Single-Walled Carbon Nanotube Patterning
Christine Micheel 1 , Luisa Bozano 1 , Jennifer Cha 1
1 , IBM, San Jose, California, United States
Show AbstractAn important goal for carbon nanotube electronics is their placement and orientation on patterned sufaces. Solubilizing single-walled carbon nanotubes (SWNTs) using functionalized DNA has been shown to be an effective method for nanotube purification and modification. This paper presents the results of patterning thiolated-DNA-wrapped SWNTs across pairs of gold lines with varying line and space widths. Through the use of the modified DNA, it is possible to effect control over nanotube position and orientation by drying drops of SWNT solutions on the patterned substrates. A goal of this project is to extend patterning capability to other metal and semiconductor surfaces using a variety of DNA modifications. SWNTs and surfaces were characterized using AFM, TEM, and SEM.
9:00 PM - EE6.2
Systematic Characterization of Carbon Nanotubes Functionalized by CF4 Plasma Fluorination by Means of Transmission Electron Microscopy.
Kaoru Shoda 1 , Seiji Takeda 1
1 Department of Physics, Graduate School of Science, Osaka University, 1-16 Machikane-yama, Toyonaka, Osaka, Japan
Show Abstract9:00 PM - EE6.3
Microscopic and Spectroscopic Study of Interactions Between Amphiphilic Peptides and Single-Walled Carbon Nanotubes.
Vasiliki Poenitzsch 1 , Hui Xie 2 , Alan Dalton 3 , Gregg Dieckmann 1 2 , Inga Musselman 1 2
1 Department of Chemistry, University of Texas at Dallas, Richardson, Texas, United States, 2 NanoTech Institute, University of Texas at Dallas, Richardson, Texas, United States, 3 Department of Physics, University of Surrey, Guildford United Kingdom
Show AbstractChanges to the electronic structure of single-walled carbon nanotubes (SWNT) through functionalization are of fundamental importance to potential SWNT-based molecular devices and sensors. We have previously demonstrated that a designed polypeptide, denoted nano-1, disperses individual SWNTs and promotes their assembly into novel hierarchical structures. In this study, we examine the effect of noncovalent protein functionalization on the electronic properties of SWNTs using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). STM images generally show that nano-1 efficiently coats and orderly associates with the SWNT surface. STS measurements, as well as shifts in certain Raman peaks, are suggestive of a charge transfer interaction between the SWNT and the peptide. Nano-1 folds into an amphiphilic α-helix in which the phenylalanine (Phe) residues on the hydrophobic face interact via π-stacking with the aromatic surface of the SWNT. The ability of electron donating (hydroxyl) and withdrawing (nitro) groups on the phenyl ring of Phe to affect the interactions between the peptide and SWNTs are examined by substituting the Phe residues in the nano-1 sequence with tyrosine and p-nitro phenylalanine, respectively. Atomic force microscopy measurements and optical absorption spectroscopy, in conjunction with circular dichroism, Raman, STM, and STS analyses, reveal that the ability to disperse individual SWNTs increases with increasing electron density of the aromatic residue on the hydrophobic face of the amphiphilic helical peptides.
9:00 PM - EE6.4
Grafting BN Nanotubes with Polymers and Carbon.
Chunyi Zhi 1 , Tang ChengChun 1 , Bando Yoshio 1 , Golberg Dmitri 1 , H. Kuwahara 2
1 , National Institute for Materials Science,, Tsukuba Japan, 2 , Innovation Research Institute,Teijin Ltd., Iwakuni, Yamaguchi, Japan
Show Abstract9:00 PM - EE6.5
Dispersion of Single-walled Carbon Nanotubes in Water with a Polyphosphazene Polyelectrolyte and Preparation of a Carbon Nanotube/polymer Nanocomposite Thin Film.
Hye Jin Park 1 , Hye Young Heo 1 , Seung Cheol Lee 1 , Min Park 2 , Sang-Soo Lee 2 , Junkyung Kim 2 , Ji Young Chang 1
1 School of materials science and engineering, Seoul National University, Seoul Korea (the Republic of), 2 Polymer Hybrids Research Center, Korea Institute of Science and Technology, Seoul Korea (the Republic of)
Show Abstract9:00 PM - EE6.8
Design of Chemical Structure of a Dispersant for Single-Walled Carbon Nanotubes in Organic Solvent
Jin-Hyon Lee 1 , In-Sung Cha 1 , Ki Kang Kim 2 , Seon-Mi Yoon 3 , Jae-Young Choi 3 , Jeonghee Lee 3 , Kay Hyeok An 2 , Young Hee Lee 2 , Ungyu Paik 1
1 Division of Advanced Materials Science Engineering, Hanyang University, Seoul Korea (the Republic of), 2 Carbon Nanotube Research Laboratory, Department of Physics, Center for Nanotubes and Nanostructured Composites, Sungkyunkwan Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon Korea (the Republic of), 3 Display Device & Material Lab., AE Center , Samsung Advanced Institute of Technology, Suwon Korea (the Republic of)
Show AbstractThe effect of chemical structure of dispersant on dispersion of single walled carbon nanotubes (SWCNTs) was investigated. The 3-hexylthiophene was used as a starting material to design a dispersant for dispersion of SWCNTs in organic solvent by varying number of head groups (thiophene), regio-regularity of head groups, and head to tail ratios (hexyl group). The SWCNT solutions were characterized with UV-Vis-NIR spectroscopy and transmission electron microscopy (TEM). It was found that the increase of number of head groups enhanced the dispersion properties of SWCNTs. Furthermore, both regio-regularity and head to tail ratios also played a significant role in the dispersion of SWCNTs. Raman spectroscopy and X-ray photoelectron spectroscopy indicated that sulfur atoms in the head group of thiophene enhanced interactions between thiophenes and the SWCNT walls. We demonstrate that it is possible to prepare highly dispersed SWCNTs solution with long-term dispersion stability using our designed thiophene (H12,RR) even under the extremely low dispersant concentration for dispersion of SWCNTs (the weight ratio of CNTs/dispersant = 1, dispersant concentration = 0.1 g/L).
9:00 PM - EE6.9
Relation of the Number of Cross-links and Mechanical Properties of Multi-Walled Carbon Nanotube Films Formed by a Dehydration Condensation Reaction
Yoshinori Sato 1 , Shin-ichi Ogino 1 , Go Yamamoto 2 3 , Kenichiro Sasamori 4 , Hisamichi Kimura 4 , Toshiyuki Hashida 3 , Kenichi Motomiya 1 , Jeyadevan Balachandran 1 , Kazuyuki Tohji 1
1 Graduate School of Environmental Studies, Tohoku University, Sendai Japan, 2 Institute of Fluid Science, Tohoku University, Sendai Japan, 3 Fracture and Reliability Research Institute, Graduate School of Engineering, Tohoku University, Sendai Japan, 4 Institute for Materials Research, Tohoku University, Sendai Japan
Show AbstractCarbon nanotubes (CNTs) films have been utilized in the form of sensor electrodes and actuators. Multi-walled carbon nanotubes (MWCNTs) are made up of more than one layer that form concentric graphene tubes that possess metallic properties and high mechanical strength. However, it is more difficult to form MWCNT films in comparison to forming single-walled carbon nanotube (SWCNT) films since MWCNTs are more rigid due to the large number of concentric graphene tubes. To date, researchers have reported on the chemical polymerization of short carboxylic SWCNTs into “rings” or “large strands” by application of a condensation reaction. Ester bonds can be synthesized by a dehydration condensation reaction of a carboxylic group with a hydroxyl group in the presence of a dehydration-condensation-coupling agent. This reaction is also useful in generating nanotube assemblies such as films in an effort to solve the aforementioned problem. Here, we report on the ester cross-linking of MWCNTs into thin films by employing a dehydration condensation reaction (esterification) with the assistance of 1,3-dicyclohexylcarbodiimide (DDC), and estimate the number of ester cross-links involving MWCNTs and examine the mechanical properties such as tensile strength and Vickers hardness. Confirmation that MWCNT films cross-linked through ester bonds were prepared by a condensation reaction in the presence of 1,3-dicyclohexylcarbodiimide (DCC) was determined by Fourier transform-infrared spectroscopy. Assuming that the ester bonds are uniformly formed all over the condensed-MWCNT films, the ratio of the number of ester cross-links and carbon atoms of the nanotubes per unit apparent volume (cm3) of condensed-MWCNT films was 5.27×10-3 using TGA. The tensile strength of condensed-MWCNT films achieved an average of 15 MPa, and is 3.1 times in comparison to those of hydrophile-MWCNT films. The mechanical properties of condensed-MWCNT films might be significantly improved through a condensation reaction by making improvements in ester cross-linking such as chemical modifications with a large number of carboxylic acid and hydroxyl groups thereby increasing the amount of condensation through dense contacts between each carbon nanotube.
EE7: Poster Session: Nanotubes and Nanowires; Spectroscopic Properties and Medical and Clinical Applications
Session Chairs
Phaedon Avouris
Stephen Doorn
Jie Liu
Pehr Pehrsson
Wei Zhao
Wednesday AM, April 11, 2007
Salon Level (Marriott)
9:00 PM - EE7.1
Evaluation of Nanotubes Concentration in Solution via UV – Visible SpectroscopySpectroscopy.
Oren Regev 1 , Rajagopalan Thiruvengadathan 1 , Attal Shay 1
1 Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva Israel
Show Abstract9:00 PM - EE7.2
Single Particle SERS Investigations of Individual Carbon Nanotubes.
Matteo Scolari 1 , Tilman Assmus 2 , Fu Nan 1 , Anton Myalitsin 1 , Marko Burghard 2 , Alf Mews 1
1 , University of Siegen, Siegen Germany, 2 , Max Planck Institute , Stuttgart Germany
Show Abstract9:00 PM - EE7.3
Possible Role Of Defects In The Visible Photoluminescence From Single Walled And Multiwalled Carbon Nanotubes.
Pravat Giri 1 2 , Dilip Singh 2
1 Department of Physics, Indian Institute of Technology Guwahati, Guwahati, Assam, India, 2 Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati India
Show AbstractSingle walled (SWNT) and multiwalled carbon nanotubes (MWNT) grown by chemical vapor deposition have been studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, and photoluminescence (PL) spectroscopy, Fourier transform infrared absorption (FTIR) and electron paramagnetic resonance (EPR) techniques. FTIR studies of the nanotubes show presence of impurities like hydrogen and oxygen in the nanotube structures. Raman scattering studies on both the samples show a number of well-resolved peaks corresponding to radial breathing mode, D-band and G-band and intermediate frequency modes (IFM) etc. Room temperature PL studies on SWNT and MWNT samples show two broad emission peaks in the visible region centered at ~2.3 eV and ~2.1 eV. These emission bands are weak and almost identical in SWNTs and MWNT samples, and are far beyond the fundamental band gap of the semiconducting CNTs. EPR measurements at room temperature show broad spectra with some differences in SWNT and MWNT samples. The spectra can be fitted with multiple peaks and the g-values derived from the spectra indicate presence of defects that act as the traping sites for electrons and presence of metallic impurities in these samples. We relate the IFM Raman modes to the structural defects in the nanotube wall. Possible origin of the visible PL is discussed in the light of defects and impurities as detected by FTIR and EPR studies on the nanotubes.
9:00 PM - EE7.5
Assembly and Optical Properties of Single-Walled Carbon Nanotubes Functionalized with Streptavidin-Coated Gold Nanoparticles
Samuel Penwell 1 , Kevin Metz 1 , John Wright 1 , Robert Hamers 1 , Wei Zhao 2
1 Chemistry Department, University of Wisconsin, Madison, Wisconsin, United States, 2 Chemistry Department, University of Arkansas, Little Rock, Arkansas, United States
Show AbstractThere is great interest in using single-walled carbon nanotubes (SWNTs) as a biomarker for medical applications based on their unique near infrared fluorescence. SWNTs also present strong Raman bands like G band at 1586 cm-1 which can be enhanced by near infrared excitation. The G band may also serve as a marker for biosensing applications. For applications requiring improved sensitivity, it is interesting to explore the surface-enhanced Raman effects of gold nanoparticles on SWNTs by assembling gold nanoparticles on SWNT surface. Here we have prepared surfactant dioctyl sodium sulfosuccinate (DSS) encased SWNT suspensions in aqueous solution. The suspensions present sharp near infrared absorption bands of first interband transitions of individual nanotubes, which are similar to those of surfactant sodium dodecyl sulfate (SDS) encased SWNT suspensions. The assembly of gold nanoparticles on SWNT sidewalls has been achieved by using interlinker straptavidin–coated gold nanoparticles which attach to the sidewell of nanotubes through the charge transfer interaction of straptavidin amine groups with SWNTs. The resulting suspensions of the gold-SWNT hybrids still show sharp near infrared absorption bands, suggesting no SWNT bundle formation after the assembly. SEM confirms the coverage of gold nanoparticles on SWNT sidewalls. The relationship between gold nanoparticle coverage density and SWNT Raman intensity will be discussed in detail in this presentation.
Symposium Organizers
Wei Zhao University of Arkansas
Pehr E. Pehrsson Naval Research Laboratory
Stephen K. Doorn Los Alamos National Laboratory
Jie Liu Duke University
Phaedon Avouris IBM T. J. Watson Research Center
Symposium Support
Army Research Office
EE8: Electrical Properties and Electronics of Nanotubes and Nanowires I
Session Chairs
Wednesday AM, April 11, 2007
Room 2016 (Moscone West)
9:00 AM - **EE8.1
Challenges in Carbon Nanotube Electronics.
Moonsub Shim 1
1 Materials Science and Engineering, University of Illinois, Urbana, Illinois, United States
Show AbstractInherent large surface-to-volume ratio in nanoscale materials can lead to properties that are highly sensitive to minute changes in the local environment. Single-walled carbon nanotubes, where all atoms are at the surface, represent, in many aspects, the ultimate limit in extreme sensitivity. However, such sensitivity has led to many difficulties from debates over the “true” intrinsic properties to major challenges in technological applications. Developing carbon nanotube-based high performance electronics has been, in particular, hampered by challenges related to this high sensitivity including difficulties in controlled doping and reliably achieving electronic homogeneity and uniform performance. I will discuss our recent studies related to the sensitive properties of carbon nanotubes from fundamental aspects such as electron-phonon coupling and phonon softening in metallic nanotubes to prospects of exploiting the sensitivity for achieving electronic homogeneity as well as doping, efficient gating, and horizontally aligning nanotubes.
9:45 AM - EE8.3
Prediction of Five-fold Increase in Current Gain of Optimally Aligned CNT Network over Random Networks
Ninad Pimparkar 1 , Coskun Kocabas 2 , Seong Kang 3 , John Rogers 2 3 4 , Muhammad Alam 1
1 School of Computer and Electrical Engineering, Purdue University, West Lafayette, Indiana, United States, 2 Department of Physics, University of Illinois, Urbana-Champaign, Illinois, United States, 3 Materials and Science Engineering, University of Illinois, Urbana-Champaign, Illinois, United States, 4 Chemistry, University of Illinois, Urbana-Champaign, Illinois, United States
Show Abstract
Nanobundle thin film transistors (NB-TFT) based on random networks of single wall carbon nanotube (SWCNT) are possible higher performance alternative to a-Si technology for macroelectronics applications (Snow, JVST04, APL05, Foygel PRB05). Here, we use stick percolation model to study the effect of alignment on the performance of NB-TFTs. In this paper for the first time, we (i) use a recently developed alignment technique (Kocabas JACS06, Small05) to fabricate NB-TFT devices with multiple densities (D), alignment (θ), channel length (Lc) and tube length (Ls), (ii) interpret the experimental data with a stick-percolation model to develop a comprehensive theory of NB-TFT for arbitrary (D, θ, Ls, Lc), and (iii) our simulations predict that a five fold increase in current gain (over existing designs) is possible with optimized transistor structure.
The NB-TFT drive current, Ion, is proportional to the number of paths and goes inversely as the average path length. Aligning the tubes partially improves Ion by decreasing average path length, however it also reduces the number of available paths for a long channel (Lc > Ls) transistor. This can lead to a decrease in Ion due to lesser number of tubes intersecting to form percolating networks. The above trade-off gives a point of optimal alignment for CNT networks and aligned NB-TFT requires a more careful design than previously anticipated (Du, PRB05).
Here, we report experiments and theoretical simulations that systematically probe the effects of degree of alignment on Ion. The experimental two-terminal drive current (Ion) vs. θ is characterized by the three counter-intuitive features: (a) Ion is maximized by an optimum distribution in between random and aligned network, (b) Ion of the optimally aligned network is approximately 20-40% higher compared to Ion of the random NB-TFT, and (c) Finally, Ion degrades rapidly as perfect alignment is achieved.
Remarkably, (i) our stick-percolation model, quantitatively reproduces all the three experimental features discussed above and predicts 20-40% gain in optimally aligned network over the random network for Lc>>Ls, (ii) the simulations suggest that more alignment is needed to optimize the performance and % improvement increases with decreasing Lc and (iii) for Lc << Ls, the improvement could be as high as 100% over the completely random networks which is a five fold increase in current gain over the existing designs.
In summary, we have used novel fabrication, characterization, and modeling to consistently interpret, for the first time experiments involving NB-TFTs with partially/fully aligned nanotube networks. We have also demonstrated the possibility of simulation-guided optimization of transistor performance as a function of density, alignment and length of CNTs.
10:00 AM - EE8.4
Effects of High Energy Proton Irradiation on Electrical Properties of One-Dimensional Nanostructure Field Effect Transistors
Woong-Ki Hong 1 , Tae-Wook Kim 1 , Gunho Jo 1 , Sunghoon Song 1 , Soon-seen Kwon 1 , Kurt E. Geckeler 1 , Kwanwoo Shin 2 , Takhee Lee 1
1 , GIST, Gwangju Korea (the Republic of), 2 , Sogang University, Seoul Korea (the Republic of)
Show AbstractOne-dimensional nanostructures such as carbon nanotubes(CNTs) and nanowires (NWs) have been extensively studied as building blocks for nanoscale electronic devices. CNTs are promising materials in a wide range of emerging technologies such as nanotube field effect transistors (FETs), quantum-effect devices, field emitters, and sensors due to their unique electrical properties [1]. In addition, ZnO NWs are one of the most promising materials for nanoscale devices such as ultraviolet lasers, light-emitting diodes, photodetectors, chemical sensors, and solar cells due to direct wide-bandgap (3.37 eV) semiconductor with large exciton binding energy (60 meV) [2-3]. In particular, for future use of these nanostructure devices in aerospace environment, information on the effects of various types of irradiation on such devices is important for developing radiation-robust devices and circuits. In this regard, the effects of electrons and heavy ions irradiation on CNTs [4-5] and proton radiation effects of ZnO NW FETs with organic gate dielectrics [6] have recently been reported. In our study, we investigated the effects of high energy proton irradiation on the electrical performance of field effect transistors (FETs) using CNTs and ZnO NWs. Proton beams of 10-35 MeV were used and the total fluences during the proton irradiation were approximately 10^11-10^12 cm^-2. These proton beams are comparable to the aerospace radiation environment For CNT-based FETs of either metallic or semiconducting SWNT networks, a set of source-drain current versus voltage characteristics (IDS-VDS) at different gate voltages showed no significant change after the proton irradiation, indicating that the SWNT network FETs are very tolerant to high energy proton beam. For ZnO NW FETs, the electrical properties were affected under the proton irradiation. After the irradiation, the IDS-VDS characteristics for ZnO NW FETs exhibited the phenomena similar to the short channel effects in MOSFETs.[1] M. S. Dresselhaus et al., Carbon Nanotubes: Synthesis, Structure properties and Applications, Berlin, Germany: Springer-Verlag, 2001. [2] P. Yang et al., Adv. Funct. Mater. 12, 323 (2002). [3] B. B. Jason et al., Appl. Phys. Lett. 86, 053114 (2004). [4] A. V. Krasheninnikov et al., Phys. Rev. B. 63, 245405 (2001).[5] H. Stahl et al., Phys. Rev. Lett. 85, 5186 (2000).[6] J. Sanhyun et al., Appl. Phys. Lett. 89, 073510 (2006).
10:15 AM - EE8.5
Excitons and Biexcitons in Carbon Nanotube Devices.
Thomas Pedersen 1
1 Dept. of Physics and Nanotechnology, Aalborg University, Aalborg East Denmark
Show AbstractExcitons dominate the optical response of semiconductor carbon nanotubes. However, at sufficiently high excitation densities, multi-exciton complexes such as biexcitons become important. These species are therefore highly relevant for nonlinear optical applications and light emission under high injection conditions. We describe the basic properties of excitons and biexcitons [1,2,3] in carbon nanotubes including the dependence on radius and chirality. The stability and experimental signatures of biexcitons predicted from theory [3] and confirmed experimentally [4] are compared. Novel results for the third order nonlinear response of excitons and biexcitons are presented. The influence of excitonic effects on the extremely large and fast nonlinearity of carbon nanotubes is discussed with emphasis on the consequences for nonlinear optical applications such as saturable absorbers and optical limiting devices.1.T.G. Pedersen, Phys. Rev. B67, 073401 (2003).2.T.G. Pedersen, Carbon 42, 1007 (2004). 3.T.G. Pedersen, K. Pedersen, H. Cornean and P. Duclos, Nano Lett. 5, 291 (2005).4.Y.Z. Ma et al., Molecular Physics 104, 1179 (2006)
10:30 AM - EE8.6
Upscaling Dielectrophoretic Nanotube Separation and Probing Dielectrophoretic Force Fields.
Sabine Blatt 1 , Christoph Marquardt 1 , Ines Klugius 1 , Aravind Vijayaraghavan 1 , Ralph Krupke 1 2
1 Institut für Nanotechnologie, Forschungszentrum Karlsruhe, Karlsruhe Germany, 2 Physikalisches Institut, Universität Karlsruhe, Karlsruhe Germany
Show Abstract10:45 AM - EE8: Elec
Break
11:00 AM - EE8.7
Scaffolding Carbon Nanotubes into Single-Molecule Circuitry
Philip Collins 1 , Brett Goldsmith 1 , Vaikunth Khalap 1 , John Coroneus 2 , Alex Kane 1 , Gregory Weiss 3
1 Physics and Astronomy, Univ. of California, Irvine, Irvine, California, United States, 2 Molecular Biology and Biochemistry, Univ. of California, Irvine, Irvine, California, United States, 3 Chemistry, Univ. of California, Irvine, Irvine, California, United States
Show AbstractAs electronic devices shrink to the nanometer scale, the relative importance of individual chemical bonds becomes larger and larger. Single-walled carbon nanotubes (SWNTs) represent an extreme limit of this rule. We have developed techniques for finding, creating, and altering single defect sites in SWNTs, and this presentation will focus on this single-site experimentation. The techniques do not rely on submicrometer lithography or precision mechanical manipulation, but instead uses circuit conductance to monitor and control covalent attachments to electrically-connected SWNTs. Discrete changes in the circuit conductance reveal chemical processes happening in real-time and allow SWNT sidewalls to be deterministically broken, reformed, and conjugated to target species. We routinely functionalized pristine, defect-free SWNTs at one, two, or more sites, and demonstrate three-terminal devices in which a single-molecule attachment controls the electronic response.
11:15 AM - EE8.8
High Performance Electronics Based on Aligned Carbon Nanotube Arrays
Coskun Kocabas 1 , Seong Kang 2 , John Rogers 2
1 Physics, 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 AbstractWe have developed a guided growth technique for producing nearly perfectly aligned, dense arrays of individual single walled carbon nanotubes (SWNTs) with nearly perfectly linear geometries. Such arrays are ideally suited to applications in thin film electronic devices, in which the arrays of tubes function as effective semiconductor thin films. This talk presents the growth technique and describes implementation of the arrays in high performance field effect transistors. We will discuss the details of the electrical properties of these devices and their variation with channel length, at DC and at frequencies into the GHz range. The results suggest significant promise for this approach to scalable high performance electronics based on carbon nanotubes.
11:30 AM - EE8.9
Aligned Carbon Nanotubes Composites.
Shamim Mirza 1 , Haim Grebel 1
1 Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, New Jersey, United States
Show Abstract11:45 AM - EE8.10
Correlating Nanostructure with Electrical transport characteristics in Carbon nanotube Y-junctions for novel electronics
Jeongwon Park 1 , Chiara Daraio 3 , Sungho Jin 1 , Apparao Rao 2 , Prabhakar Bandaru 1
1 Materials Science program, UC, San Diego, La Jolla, California, United States, 3 Applied Physics, California Institute of Technology, Pasadena, California, United States, 2 Department of Physics, Clemson University, Clemson, South Carolina, United States
Show AbstractCarbon Nanotube (CNT) based electronics offer significant potential, as a nanoscale alternative to silicon based devices, for novel molecular technologies. So far, the use of nanotubes and nanowires has mainly focused on adopting the MOSFET (Metal-Oxide Semiconductor Field Effect Transistor) paradigm, where a nanotube serves as the channel between lithographically fabricated electrodes (viz., Source and Drain), and an electrically insulated gate modulates the channel conductance. To realize truly nanoelectronic architecture, it is desirable to have a fully integrated nanotube based technology, where both devices and interconnects are based on CNTs. Additionally, it would be attractive to harness new functionalities, peculiar to novel CNT forms such as Y-junctions. We report on the correlation of the electrical properties with the detailed stucture of CNT based Y-junctions, with the ultimate aim of inventing new types of nanoelectronic components. The Y-junction morphologies are shown to have a natural asymmetry at the junction region due to the presence of non-hexagonal defects- required for energy minimization. The carrier delocalization and the inevitable presence of catalyst particles (1), introduced during growth, can induce a net charge and scattering which can be exploited in constructing electronic devices. Through detailed Transmission Electron Microscopy (TEM) studies and electrical impedance measurements on these CNT Y-junctions we show the possibilities of nano-engineering these structures. We will also present results on the switching and transistor characteristics of these junctions, where we have seen (2)inverting/switching behavior, up to 100 kHz. An electrical impedance model of a MWNT Y-junction will be presented which will help gain an understanding of the current transport mechanisms in these structures.1. N. Gothard, et al. “Controlled growth of Y-junction nanotubes using Ti-doped vapor catalyst”, Nanoletters 4, 213-217 (2004).2. P. Bandaru et al, “Novel electrical switching behavior and logic in carbon nanotube Y-junctions”, Nature Materials, vol. 4(9), 663-666, (2005)
12:00 PM - EE8.11
Use of Multisegmented 1-Dimensional Hybrid Structures of Carbon Nanotube and MetalNanowires for High Performance Battery and Supercapacitor Applications
Fung Suong Ou 1 , Manikoth Shaijumon 1 , Pulickel Ajayan 1
1 Department of Material Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States
Show AbstractCarbon nanotube - metal nanowire hybrid structures were fabricated using the template approach with combination of electrochemical deposition and chemical vapor deposition (CVD) techniques. The nanotube-nanowire interfaces for different metals (Au and Cu) have been examined and studied in detail using SEM and TEM. A well-adhered interface is observed to exist between the carbon nanotube and the metal nanowires. Supercapacitor and battery devices were fabricated using these composite electrodes and their electrochemical performances have been studied using cyclic voltammetry and galvanostatic charge-discharge measurements. The CNT-metal electrodes showed low contact resistance, which can be explained from the well adhered interface formed between the CNT and metal .
12:15 PM - EE8.12
Nanoelectromechanical Structures Suspended by Carbon Nanotube Networks.
Seung Sae Hong 1 2 , Jung Hoon Bak 1 2 , Byung Yang Lee 2 , Sung Woon Cho 1 2 , Young Duck Kim 1 2 , Seunghun Hong 2 , Yun Park 1 2
1 CSCMR, Seoul National University, Seoul Korea (the Republic of), 2 Department of Physics and Astronomy, Seoul National University, Seoul Korea (the Republic of)
Show Abstract12:30 PM - EE8.13
Carbon Nanotube-Based Electrically Conductive and Optically Transparent Thin Films
Zhongrui Li 2 , Enkeleda Dervishi 1 2 , Viney Saini 1 2 , Alexandru Biris 3 , Dan Lupu 3 , Alexandru Biris 1 2
2 Nanotechnology Center, University of Arkansas at Little Rock , Little Rock, Arkansas, United States, 1 Applied Science , University of Arkansas at Little Rock, Little Rock, Arkansas, United States, 3 , National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj Napoca Romania
Show AbstractCurrent conductive transparent coatings utilize indium-tin oxide (ITO) thin films applied to an optically transparent substrate by physical vapor deposition processes, primarily sputtering. These processes require considerable cost and are difficult to scale up. Alternatively, utilizing carbon nanotubes as transparent conductor produces materials that closely match the properties of ITO in conductive transparent applications and are more cost effectively produced and are far more flexible. Performance of conductive transparent carbon nanotube films is directly tied to uniform and controlled application of high purity carbon nanotube material.Highly electrically conductive and highly optically transparent thin films were fabricated on conventional glass substrates using different purified carbon nanotubes, single-wall (SWNT), double-wall (DWNT), and multi-wall (MWNT) carbon nanotubes. The starting carbon nanotube materials were first made into homogenous solution with either sodium cholate or dimethylformamide. The two different approaches, airbrushing and membrane filtration methods, were used and compared. To further improve the performance, we also systematically studied the effect of chemical modification such as nitric acid and thionyl chloride on the optical and electric properties of carbon tubes films. This fundamental study will help to understand the optical and electrical properties of carbon nanotube based transparent and electrically conductive coating/films by modification of the applied carbon nanotube network. These films can be widely used in many optoelectronic applications including organic light emission displayers, carbon nanotube-based solar panels.
12:45 PM - EE8.14
Self Assembled Carbon Nanotubes and Electronic Functionality.
Cengiz Ozkan 1
1 Mechanical Engineering, University of California at Riverside, Riverside, California, United States
Show AbstractEE9: Electrical Properties and Electronics of Nanotubes and Nanowires II
Session Chairs
Wednesday PM, April 11, 2007
Room 2016 (Moscone West)
2:30 PM - **EE9.1
Electro-thermal Light Emission in Individual Metallic Single-walled Carbon Nanotubes.
David Mann 1 , Yuichiro Kato 1 , Eric Pop 1 , Hongjie Dai 1
1 , Stanford University, Stanford, California, United States
Show Abstract3:00 PM - **EE9.2
Super Growth: Mass Production of Catalyst-Free SWNTs, DWNT forests for FEDs, SWNT Solids for Super-Capacitors.
Kenji Hata 1
1 esearch Center for Advanced Carbon Materials, AIST, Japan, Tsukuba Japan
Show AbstractThis presentation will provide an overview of our recent development of carbon nanotube synthesis and their applications based on the “Super Growth” CVD. Super Growth CVD is an emerging approach to grow carbon nanotubes where the activity and lifetime of the catalysts are enhanced by an addition of water into the ambient of the CVD furnace. After a short introduction and overview of the super-growth CVD [1], I would talk about our development to extend this approach to grow double walled-carbon nanotube forests [2], and their application for field emission displays. Also I would present our technique to transform the sparse as-grown carbon nanotube forests into highly-densely packed material that we call SWNT solids [3]. We would demonstrate that such SWNT solid is useful for super-capacitor electrodes for compact energy storage. Finally, I would show our ongoing efforts to realize industrial scale mass-production of high-purity, long, and aligned SWNTs to establish a carbon nanotube based industry [4].References: [1] Science 306, 1362(2004), [2] Nature Nanotechnology 1, 103(2006), [3:] In print in Nature Material, [4] J. Am. Chem. Soc.; 128, 13338 (2006)
3:30 PM - EE9.3
Position Controlled Growth of Aligned Nanotubes for Transistor Applications
Bo Lei 1 , Koungmin Ryu 1 , Alexander Badmaev 1 , Lewis Gomez De-Arco 1 , Xiaolei Liu 1 , Song Han 2 , Kang L. Wang 2 , Chongwu Zhou 1
1 EE. Electrophysics, Univ. of Southern California, Los Angeles, California, United States, 2 EE, UCLA, Los Angeles, California, United States
Show AbstractWe have developed a novel nanotube-on-insulator (NOI) approach for producing nanotube devices based on aligned single-walled carbon nanotubes (SWNT) on sapphire 1, 2 and quartz. In this talk, we will present transistor studies based on nanotubes with controlled positions and orientations. First, photolithography was used to open windows on sapphire or quartz substrates followed by catalyst deposition and calcinations. Substrates with patterned catalysts then went through chemical vapor deposition (CVD) process to grow carbon nanotubes. After CVD growth, one can see highly aligned SWNT originating from catalyst islands with typical density of 2-3 nanotubes per micrometer. With these produced nanotubes, top-gated transistors have been fabricated through multiple steps. The first step was to define source/drain electrodes by photolithography followed by e-beam evaporations. The second was to deposit a dielectric layer of HfO2 on the substrates by using atomic layer deposition (ALD). The Final was to form top-gate electrodes defined by photolithography. In this study, both Ti/Au and Pd were used as source/drain contacts. The fabricated transistors with Pd contacts show on/off ratios up to 106 and subthreshold swings down to ~ 150 mV/decade. Furthermore, we demonstrate a way to controllably obtain both n- and p- type devices by controlling gate voltage polarity during electrical breakdown. Transistors made by this patterned growth approach may work as a platform for explorations of nanotube integrated circuits.1.Song Han, Xiaolei Liu and Chongwu Zhou, J. of Am. Chem. Soc. 127, 5294-5295(2005).2. Xiaolei Liu, Song Han, and Chongwu Zhou, Nano Lett, 6, 34-39 (2006).
3:45 PM - EE9.4
Novel Low Temperature Contact Transfer Methodology for Multiwalled Carbon Nanotube Bundle Applications.
Ashavani Kumar 2 , Rajashree Baskaran 1 , Alejandra Camacho 1 , Pulikel Ajayan 2
2 Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States, 1 Components Research, Intel Corp, Chandler, Arizona, United States
Show Abstract4:00 PM - EE9.5
Heterogeneously Integrated, Three Dimensional Electronics by Use of Printed Semiconductor Nanomaterials.
Jong-Hyun Ahn 1 2 3 , Hoon-Sik Kim 5 , Keon Jae Lee 1 3 , Seokwoo Jeon 1 2 3 , Seong Jun Kang 1 2 3 , Yugang Sun 1 2 3 , Ralph Nuzzo 1 3 4 , John Rogers 1 3 4
1 Department of Materials Science and 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, 3 Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 5 Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 4 Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractWe have developed a new approach to combine broad classes of dissimilar materials into heterogeneously integrated electronic systems with two or three dimensional layouts. The process begins with the synthesis of different semiconductor nanomaterials such as single walled carbon nanotubes and single crystal nanowires/ribbons of gallium nitride, silicon and gallium arsenide on separate substrates. Direct printing of high-quality, single-crystalline semiconductor nanomaterials onto a target substrate, followed by depositing, patterning other materials and interconnect formation at relatively low temperatures (< 250oC), yields high performance heterogeneously integrated electronics that incorporate any combination of semiconductor nanomaterials. Demonstrations of printed devices include ultrathin, high performance metal-oxide-semiconductor field-effect transistors (MOSFETs), metal-semiconductor field-effect transistors (MESFETs), thin film transistors (TFTs), photodiodes and other components, integrated into device arrays, logic gates and actively addressable photodetectors on rigid inorganic and flexible plastic substrates. This versatile methodology can produce a wide range of unusual electronic systems that would be impossible to achieve using other techniques.
4:15 PM - EE9: Elec
Break
4:30 PM - **EE9.6
Piezoelectric Nanogenerators for Self-powered Nanosystems.
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. 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]Z.W. Pan, Z.R. Dai and Z.L. Wang* “Nanobelts of semiconducting oxides”, Science, 291 (2001) 1947-1949 [The most cited paper in chemistry in 2001-2003 (ISI); having been cited over 1100 times].[2] X.Y. Kong, Y. Ding, R.S. Yang, Z.L. Wang* "Single-crystal nanorings formed by epitaxial self-coiling of polar-nanobelts ", Science, 303 (2004) 1348-1351.[3] P.X. Gao, Y. Ding, W.J. Mai, W.L. Hughes, C.S. Lao and Z.L. Wang* “Conversion of Zinc Oxide Nanobelt into Superlattice-Structured Nanohelices”, Science, 309 (2005) 1700-1704.[4] Z.L. Wang* and J.H. Song “Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays”, Science, 312 (2006) 242-246.[5] for details visit: http://www.nanoscience.gatech.edu/zlwang/
5:15 PM - EE9.8
Scaling Effects of Channel Length in In2O3 Nanowire Field Effect Transistors Studied by Conducting Atomic Force Microscopy.
Gunho Jo 1 , Jongsun Maeng 1 , Tae-Wook Kim 1 , Woong-Ki Hong 1 , Minseok Jo 1 , Hyunsang Hwang 1 , Takhee Lee 1
1 Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju Korea (the Republic of)
Show AbstractMetal oxide nanowires such as ZnO, SnO2, CdO, and In2O3 have recently been extensively studied for their electronic, photonic, and biological sensing device applications. Of these, In2O3 nanowires have notably been used as nanoelectronic building blocks for transistors, memory devices, and highly sensitive sensors. However, the majority of research on In2O3 or other metal oxide nanowires has typically focused on diameter-controllable synthesis and device applications, such as field effect transistors (FETs) with micron-sized channel lengths [1]. To this end, the scaling effects of channel length have not been extensively studied in nanowire FET devices, as compared with conventional metal oxide semiconductor field effect transistors (MOSFETs) [2]. It is important to explore the scaling effects of the electrical properties of nanowire FET devices as channel length decreases before developing possible applications in highly integrated nanowire electronics. Recently, Yaish et al [3] have directly measured the contact resistance in semiconducting carbon nanotubes using a conducting atomic force microscope (CAFM). Using the CAFM technique, we investigated the scaling effects of the channel length in In2O3 nanowire FETs. We changed the channel length by placing CAFM tip on a controlled position of In2O3 nanowire. As the channel length decreased from 1 µm to 20 nm, scale effects of the channel length were observed, i.e., the threshold voltage shifted in the negative gate bias direction, the source-drain current (IDS) and transconductance (gm) increased, and mobility decreased, as the channel length decreased. We analyzed the threshold voltage dependence on the channel length using empirical relationships of power-law, described as IDS ∝ L-α and gm ∝ L-β, where α and β are fitting parameters of the scaling effect in the channel length, determined as 0.47 and 0.34, respectively. Accordingly, the threshold voltages, VT ∝ Lβ-a exhibited the dependence of L-0.13. Also, we studied the scaling in the carrier mobility (µ) of the In2O3 nanowire FET; µ exhibited L0.66 dependence. These results showed the channel length dependence of the threshold voltage and mobility in the short channel regime, which is in excellent agreement between the experimental data and the calculated data using scaling parameters (α and β) of current and transconductance. [1] D. Zhang, C. Li, S. Han, X. Liu, T. Tang, W. Jin, and C. Zhou, Appl. Phys. Lett. 82, 112 (2003). [2] M. Ieong, B. Doris, J. Kedzierski, K. Rim, and M. Yang, Science, 306, 2057 (2004). [3] Y. Yaish, J.-Y. Park, S. Rosenblatt, V. Sazonova, M. Brink, and P. L. McEuen, Phys. Rev. Lett. 92, 046401 (2004).
5:30 PM - EE9.9
Nanowire MOSFET with Doped Epitaxial Contacts for Source and Drain.
G. Cohen 1 , M. Rooks 1 , J. Chu 1 , P. Solomon 1 , S. Laux 1 , J. Ott 1 , R. Miller 1 , W. Haensch 1
1 , IBM T.J. Watson Research Center, Yorktown Heights, New York, United States
Show AbstractWe report the fabrication and electrical characteristics of p-MOSFETs and n-MOSFETs with a silicon nanowire channel and doped silicon source and drain regions. The process we used thickens the nanowire body in the regions where a source and a drain are formed similarly to the raised source-drain approach practiced in silicon-on-insulator technology. Unipolar characteristics were achieved in both n-FET and p-FET devices.
The silicon nanowires were synthesized by the Vapor-Liquid-Solid (VLS) method in a UHV-CVD chamber, with silane as the silicon precursor and gold as the catalyst. The typical nanowire body had a uniform diameter of 25 nm and had no intentional doping.
To fabricate devices we etched off the gold catalyst and transferred nanowires onto a host wafer. The host wafer consisted of a heavily doped silicon substrate capped by a thin dielectric stack of silicon dioxide and silicon nitride. The host wafer was later used for back-gating the nanowire FETs. A dielectric film of silicon oxide and silicon nitride was blanket deposited over the nanowires, and patterned with contact holes to expose the segments of the nanowire where the source and drain regions are fabricated. For p-FETs, the source and drain regions were formed by adding boron doped silicon to the exposed nanowire body using in-situ doped silicon epitaxy. For n-FETs, the epitaxial source and drain regions were grown undoped and were later implanted with P and As. The source-drain epitaxy was carried out in a UHV-CVD chamber equipped with silane and diborane as precursors. A 1000°C/5sec rapid thermal annealing was used to activate the implanted dopants. Self-aligned nickel silicide was used to form contacts to the source and drain.
The measured Id-Vg characteristic of the device exhibited unipolar transport, while reference FETs made with nanowires from the same batch but with Schottky (metal) contacts exhibited ambipolar characteristics. For n-FETs with a 0.4 μm long gate and a nanowire body diameter of 25 nm, we measured an Ion of 5.1 μA at Vdd=1V and an Ion/Ioff ratio of 1E6. For p-FET with similar dimensions we measured Ion of 0.95 μA at Vdd=-1V, an Ion/Ioff ratio of 1E6, and a subthreshold slope of 200mV/dec.
5:45 PM - EE9.10
Integrated Complementary Nanowire Logic Gates towards Power Efficient Circuitries
Dunwei Wang 1 , James Heath 1
1 , Caltech, Pasadena, California, United States
Show AbstractEE10: Poster Session: Electrical Properties and Electronics of Nanotubes and Nanowires
Session Chairs
Phaedon Avouris
Stephen Doorn
Jie Liu
Pehr Pehrsson
Wei Zhao
Thursday AM, April 12, 2007
Salon Level (Marriott)
9:00 PM - EE10.1
Nano-Silicon Thermoelectrics.
Akram Boukai 1 , Yuri Bunimovich 1 , James Heath 1
1 Chemistry, Caltech, Pasadena, California, United States
Show AbstractNanoscale materials may have the potential to dramatically enhance the efficieny of a thermoelectric device. Here we present recent experimental work on strained silicon nanowires and silicon quantum dots as potentially efficient thermoelectric materials. The thermopower, electrical conductivity, and thermal conductivity are measured and discussed.
9:00 PM - EE10.10
Bromine doped, High Performance Single Walled Carbon Nanotube Thin Film Transistors.
Husnu Unalan 1 , Giovanni Fanchini 2 , Manish Chhowalla 2
1 Electrical Engineering Division, Engineering Dept., University of Cambridge, Cambridge United Kingdom, 2 Materials Science and Engineering, Rutgers University, Piscataway, New Jersey, United States
Show Abstract9:00 PM - EE10.11
Characterization of Bending Eigenmodes of Carbon Nanotube Resonator Devices.
Daniel Garcia-Sanchez 2 , Alvaro San Paulo 1 , Maria Esplandiu 2 , Francesc Perez-Murano 1 , Albert Aguasca 3 , Adrian Bachtold 2
2 , Institut Catala de Nanotecnologia, Bellaterra Spain, 1 , Centro Nacional de Microelectrónica, Bellaterra Spain, 3 , Universitat Politecnica de Catalunya, Barcelona Spain
Show Abstract9:00 PM - EE10.12
Resistance Switching in Ionic Nanowires.
David Schoen 1 , Chong Xie 1 , Yi Cui 1
1 Materials Science and Engineering, Stanford University, Stanford, California, United States
Show AbstractResistance switching in copper and silver chalcogenide ion conductors has been explored for its application to nonvolatile memory. This study investigated resistance switching in chemically synthesized silver chalcogenide nanowires. Silver selenide nanowires have been synthesized from selenium nanowire templates and their phase composition before, after, and during low temperature annealing has been characterized by transmission electron microscopy. The electrical behavior of these nanowires has also been characterized after similar annealing regimens. Wires as synthesized have the equilibrium Ag2Se orthorhombic crystal structure, but after annealing above 140 °C the wires have a tetragonal crystal structure. This phase behavior is correlated with a change in the electrical behavior. Wires annealed above 140 °C display a volatile resistance switching above a threshold voltage with a very high on-off resistance ratio of 10^7 and an anomalously high off resistance.
9:00 PM - EE10.13
Towards Understanding of the Interplay between Surface Processes and Electron Transport in quasi-1D Metal Oxides
Andrei Kolmakov 1
1 Physics, SIUC, Carbondale, Illinois, United States
Show AbstractIn spite of the growing amount of exiting demonstration of the superior performances of nanowire based chemical sensors the fundamental understanding of the size/shape specific surface properties and their interplay with the electron/hole transport and optical properties of the nanowires is still in infancy. The later is due to experimental challenges related with the fabrication of appropriate nanowires and the limited selection of tool specifically sensitive to surface properties. We have developed and tested few experimental UHV compatible approaches to grow the nanostructures and fabricate the model gas sensing nanowire devices to probe surface properties via transport measurements. The adsorption-desorption events as well as simple chemical reactions were monitored in the model well defined vacuum conditions as well in realistic air environment. Thus, so called, pressure gap has been bridged. We have implemented new methods to monitor in situ the surface processes in individual nanostructures during their sensitization with catalyst particles and formation of radiation defects during electron and ion beam irradiation. The influence teh above treatments on the surface reactivity and selectivity has been directly demonstrated. We have tested a range of spectroscopy and imaging techniques to address local transport particularities taking place in the individual operating metal oxide nanostructure sensor. In particular, in collaboration with nano-transport group at ORNL, we were using an array of Scanning Potential (SPM) and electron microscopies to visualize the potential distributions and electronic action of the local defects and electrical contacts in an operating device. We also have successfully implemented of synchrotron radiation based photoelectron emission spectro-microscopy (PEEM) to explore submicron compositional and electronic (work function) inhomogeneouties in individual metal oxide nanowire wired as a chemiresistor.Benefiting from the gained knowledge and expertise, we are developing the real world prototypes for nanowire based e-noses and chemical sensors.
9:00 PM - EE10.14
Thermomechanically Compliant Metal/Carbon Nanotube/Thermoelectric Contacts
Himanshu Mishra 1 4 , Kalapi Biswas 2 4 , Timothy Fisher 1 4 , Timothy Sands 2 3 4
1 Mechanical Engineering, Purdue University, West Lafayette, Indiana, United States, 4 Birck Nanotechnology Center, Purdue University, West Lafayette , Indiana, United States, 2 Materials Engineering, Purdue University, West Lafayette , Indiana, United States, 3 Electrical & Computer Engineering, Purdue University, West Lafayette , Indiana, United States
Show AbstractThe design of thermoelectric (TE) generator and refrigerator modules is often constrained by the shear stresses that result from differential thermal expansion, both during steady-state operation and during on/off cycling. For example, the coefficient of thermal expansion values for Bi2Te3 and aluminum nitride (at 20oC) are 19 x 10-6 K-1 [J. Schilz et al., 1997] and 4.5 x 10-6 K-1 [Sirota & Golodushko, 1974] respectively. In a p-n leg of a TE refrigerator with a metal/TE interface length of the order of 1mm, a temperature difference of 50K would result in an interface mismatch of 0.7µm. The magnitude of shear stress generated at the interface for the strain is of the order of 20 MPa, which can cause failure under cyclic loading conditions.Here we report a new technique that offers the potential to address this problem by exploiting the combined mechanical and electrical properties of multiwalled carbon nanotube (MWNT) arrays to form the mechanically compliant interface material between the metal interconnects and the thermoelectric material. MWNT arrays have been reported to exhibit very high elastic modulus and fatigue strength [Dresselhaus et al., 2001]. Thin films of bismuth telluride (Bi2Te3) have been electrodeposited on dense MWNT arrays (tube density of the order of 1014 m-2) grown by microwave plasma-enhanced chemical vapor deposition (PECVD). These thermomechanically compliant metal/carbon nanotube/thermoelectric contacts are expected to operate more robustly under a thermal stress cycle. Depending on the growth conditions, the aspect ratio of MWNT arrays synthesized using a tri-layer of metal films (titanium, aluminium and iron) can vary from 100 to 1000 with individual CNT diameters of approximately 50 nm. FESEM images of these samples reveal that the MWNT array is vertically oriented. In this paper we show that, owing to large number of mechanically flexible MWNTs situated between the metal and the Bi2Te3 film, the shear stress developed in the TE film will be dramatically reduced because the intermediate MWNT array can easily deform to accommodate the different thermal expansions of the TE material and the submount. This strategy thus opens the possibility of much higher temperature operation at the existing levels of shear stress, or with negligible shear stress values with the existing temperature ranges. The electrodeposition process is carried out in a standard three-electrode cell potentiostat. The results reveal that Bi2Te3 crystals nucleate at the defect sites on the MWNT and grow on and around the tubes, ultimately extending above the MWNT array as a thin film. Using this process, films of thicknesses ranging from 1 to 5μm were obtained. The presence of polycrystalline Bi2Te3 was confirmed by powder x-ray diffraction and transmission electron microscopy analyses.
9:00 PM - EE10.15
The Carbon Nanotube Enhanced Tunneling Diode Via In Situ Highly Controlled Electric Field Induced Surface Functionalization
Alexander Austin 1 2 , Christian Estonilo 1 , Quoc Ngo 1 2 , Cattien Nguyen 2 , Shoba Krishnan 1
1 Electrical Engineering, Santa Clara University, Santa Clara, California, United States, 2 , ELORET Corporation/NASA Ames Research Center, Moffet Field, California, United States
Show AbstractThis paper presents the development of a carbon nanotube (CNT) based diode for potential nanoscale electronics. The device comprises of a junction between a multi-walled CNT (MWNT) and a hydrogen-passivated surface of highly P-doped silicon. For a MWNT in physical contact with the silicon surface, a metal-insulator-semiconductor (MIS) tunneling diode is characterized, demonstrating the metallic behavior of the MWNT as well as the creation of an ultra thin SiO2 layer on the p-Si surface through an electric-field-induced oxidation mechanism. The oxide layer is generated in situ, with sub-nanometer length scale precision in controlling the oxide thickness utilizing the one-dimensional conducting MWNT. The device exhibits a tunneling behavior with rectified conduction characteristics in the forward bias direction and a turn-on voltage in the junction depending on the oxide thickness. The potential required for oxide growth is 4V above the device operating voltage range, thus making the process for fabricating this type of diode device feasible. This allows fabrication of the complete device structure by simply adjusting the applied potential of the junction. Experimental data are obtained for two device configurations: 1) MWNT sidewall contact with the Si surface and 2) MWNT end contact with the Si surface using an atomic force microscope (AFM). In addition, we present data utilizing the Wentzel-Kramers-Brillouin (WKB) approximation for modeling tunneling currents for various thicknesses of oxide layers. Correlating with experimental data, the WKB approximation affords a tunneling current of 10 nA at a potential of 0.7V for a 5 Å oxide layer. Increasing the insulator thickness by way of the in situ oxidation technique, a 10 Å thick oxide layer exhibits 10 nA tunneling current at an applied potential of 1.5 V. Also, AFM imaging data will be presented revealing that the MWCNT creates oxide features on the order of the contact area to form the MIS junction. Control over the power consumption and operating voltage range will be demonstrated. This, in combination with the inherent rectifying nature of the MWNT-oxide-semiconducting Si junction provides predictable current and carrier transport behavior, which may have potential diode applications for future integrated circuit technology.
9:00 PM - EE10.17
Modeling and Simulation of n-Type Carbon Nanotube Field Effect Transistors Using Ca as Contact Electrodes.
Aurangzeb Khan 1 , Syed Shah Quadri 1 , Jihua Gou 2
1 Electrical and computer engineering, University Of South Alabama, Mobile, Alabama, United States, 2 Department of Mechanical Engineering, University of South Alabama, Mobile, Alabama, United States
Show Abstract9:00 PM - EE10.18
Transport Properties of Single-walled Carbon Nanotubes with Defects.
Yong Sun Kim 1 , Youngmu Oh 1 , Ji-Yong Park 1
1 Division of Energy Systems Research, Ajou University, Suwon Korea (the Republic of)
Show Abstract9:00 PM - EE10.19
Electrical Characterization and Manipulation of ZnO Nanorods with Atomic Force Microscopy.
Youngmu Oh 1 , Yong Sun Kim 1 , Ji-Yong Park 1
1 Division of Energy Systems Research, Ajou University, Suwon Korea (the Republic of)
Show Abstract9:00 PM - EE10.21
Electrothermal Contact Characterization of Metal-carbon Nanofiber Junctions for Interconnect Applications.
Quoc Ngo 1 2 , Toshishige Yamada 2 1 , Alan Cassell 2 , Jun Li 2 , Cary Yang 1
1 Center for Nanostructures, Santa Clara University, Santa Clara, California, United States, 2 Center for Advanced Aerospace Materials and Devices, NASA Ames Research Center, Moffett Field, California, United States
Show Abstract9:00 PM - EE10.22
Electrodeposition of Bismuth Telluride Nanowires for Thermoelectric Applications.
Qi Ye 1 , Raymond Scheffler 1 2 , Melanie McNeil 2
1 Center for Advanced Aerospace Materials and Devices, NASA Ames Research Center, Mountain View, California, United States, 2 Department of Chemical and Materials Engineering, San Jose State University, San Jose, California, United States
Show Abstract9:00 PM - EE10.23
Synthesis and Atomic Force Microscopy studies on Cadmium Zinc Telluride (CZT) Nanowires
Thulasidharan Gandhi 1 , Krishnan Raja 1 , Manoranjan Misra 1
1 Material Science and Metallurgical, University of Nevada, Reno, Reno, Nevada, United States
Show Abstract9:00 PM - EE10.24
Mechanical and Electrical Properties of Polymer-CNT Composites at Cryogenic Temperature.
Justin Schwartz 1 , Anita Oliver 1 , Abdallah Mbaruku 1 , Quang Le 1
1 NHMFL, FSU, Tallahassee, Florida, United States
Show Abstract9:00 PM - EE10.25
Size and Composition Dependent Memory Switching Behavior in Sub-Lithographic Ge-Sb-Te Phase-Transition Nanowires.
Yeonwoong Jung 1 , Se-Ho Lee 1 , Dong-Kyun Ko 1 , Ritesh Agarwal 1
1 Materials Science & Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States
Show Abstract9:00 PM - EE10.26
Assembly of Si and Si-Ge Core-Shell Nanowire Devices by Holographic Optical Tweezers
Yohai Roichman 1 , Jessica Lensch 2 , Lincoln Lauhon 2 , David Grier 1
1 Physics Department, New-York University, New-York, New York, United States, 2 Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States
Show Abstract9:00 PM - EE10.27
Carbon Nanotube-Titania Hybrid Nanostructures.
Shaijumon Manikoth 1
1 Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States
Show Abstract9:00 PM - EE10.28
Field-, Diameter-, and Surface State- Dependent Transport Behavior in Semiconductor Nanowires
Shadi Dayeh 1 , Paul Yu 1 , Edward Yu 1 , Deli Wang 1
1 Electrical and Computer Engineering, University of California-San Diego, La Jolla, California, United States
Show AbstractQuasi 1-dimensional semiconductor nanowires (NWs) have been intensively studied in the past decade due to their potential for nanoscale electronics and photonics. Systematic study of the carrier transport properties in NWs enables the understating of important physical phenomena at the nanoscale and provides basic parameters for the design and fabrication of functional devices and integrated systems. InAs NW field effect transistors (NWFETs) were used as a case study for this work and the NWs were grown by MOCVD on SiO2/Si substrates in the presence of Au nanoparticles, resulting in NW diameters of 60-120nm. The NWs were suspended in solution and transferred to SiO2/n+-Si substrates for device fabrication using e-beam lithography for Ti/Al source and drain ohmic contacts and Al/ZrO2-Y2O3 for top-gate/dielectric. (1) To achieve reliable assessment of the key electronic properties, we studied the transfer characteristics of these NWFETs at different gate voltage sweep rates and performed time resolved measurements which clearly exhibit transient characteristics indicative of surface state trapping and de-trapping. The surface state charge modulation alters the mobile charge density in the NWFET channel and results in a time dependent extrinsic transconductance that dramatically affects the extraction of characteristic transport parameters such as carrier mobility and density. This analysis helps to understand the discrepancy of transport parameters reported in the literature for similar NWFET devices, and more importantly, suggests that measurements with a neutralized surface state charge result in intrinsic NW transport parameters. (2) We have also investigated the effects of reducing the channel width (NW diameter) on carrier transport behavior. A large reduction in the carrier mobility has been measured as the NW diameter is reduced attributed to enhanced surface scattering that occurs when the surface area to volume ratio increases, while the average carrier concentration increased due to strong carrier accumulation at the surface caused by surface Fermi energy pinning. (3) Lastly, we have studied the effects of the lateral field on the carrier velocity in these InAs NWFETs. Extracted output characteristics exhibit a decrease in the saturation currents at high source-drain voltages and the computed drift velocity-field plots exhibit negative differential behavior with a strong degradation of the carrier mobility at high fields due to scattering or thermal effects. Although non-parabolic band structure has been predicted to dominate the negative differential mobility, especially for small bandgap materials, heating effects at elevated fields could also dominate the carrier transport by enhancing phonon scattering. Indeed, morphological changes were observed in similar NW devices subjected to high field device operation. These results also highlight thermal management as an important issue in realizing the full potential of NW based devices.
9:00 PM - EE10.3
Ultra-thick Freestanding Aligned Carbon Nanotube Films by a Self-releasing Technique.
Lijie Ci 1 , Shaijumon M. Manikoth Manikoth 1 , Xuesong Li 1 , Robert Vajtai 1 , Pulickel M. Ajayan 1
1 Department of Material Science and Engineering, Rensselear Polytechnic Institute, Troy, New York, United States
Show Abstract9:00 PM - EE10.6
Self Assembly of TiO2 Nanowires on Devices by Dielectrophoresis.
Steven Kuo 1 2 , Geetha Dholakia 1 , E. Allen 2
1 Center for Advanced Aerospace Materials and Devices, ELORET\NASA Ames Research Center, Moffett Field, California, United States, 2 Department of Chemical and Materials Engineering, San Jose State University, San Jose, California, United States
Show Abstract9:00 PM - EE10.7
High-Current Reliability of Carbon Nanofibers for Interconnect Applications.
Makoto Suzuki 1 , Hirohiko Kitsuki 1 , Quoc Ngo 1 2 , Alan Cassell 2 , Christopher Moylan 2 , Yusuke Ominami 1 , Jun Li 2 , Cary Yang 1
1 Center for Nanostructures, Santa Clara University, Santa Clara, California, United States, 2 , NASA Ames Research Center, Moffett Field, California, United States
Show AbstractCarbon nanofibers (CNFs) have attracted broad interest for various applications including on-chip interconnect and field-emission sources. To assess such potentials, especially for reliability considerations, it has become important to study high-current transport and breakdown in this material. We present a systematic reliability study of CNFs under high-current stress in three different geometrical configurations for interconnects such as CNFs (1) suspended between two electrodes, (2) resting on the underlying SiO2/Si substrate with two pre-patterned electrodes, and (3) embedded in SiO2 matrix as vertical interconnects.Detailed structural analysis of failed CNFs is performed in configuration (1) using an in situ scanning transmission electron microscopy technique, suggesting the failure mode of CNFs is strongly related to the morphology of graphite layers comprising CNFs. Correlation between the maximum current density and electrical resistivity is deduced, showing that low electrical resistivity affords high current capacity without failure. Comparison between configurations (1) and (2) indicates that the effective heat dissipation, as well as low electrical resistivity, can improve current carrying capacity of CNFs. The importance of electrical resistivity and heat dissipation for current capacity clearly shows that self-heating is one of the crucial mechanisms for the current-induced breakdown of CNFs. The vertical interconnect configuration (3) has more effective thermal dissipation via the surrounding SiO2 matrix and a more optimized electrical resistivity. This configuration allows long-term high-current reliability studies to be performed. The CNF interconnect structure does not show degradation or failure with continuous current stressing at 107 A/cm2 over 180 hours, which is clearly superior to all existing Cu interconnects.
9:00 PM - EE10.8
Gate Effects in a Field Effect Transistor based on an Individual Single-crystalline Bi Nanowire
Seunghyun Lee 1 , Wooyoung Shim 1 , Jinhee Ham 1 , Kyoungil Lee 1 , Wooyoung Lee 1
1 Dept. of Materials Science and Engineering, Yonsei University , Shinchon, Seoul, Korea (the Republic of)
Show AbstractSemimetallic bismuth (Bi) is a group V element with nusual transport properties due to a unique band structure of −38 meV in band overlaps. In particular, single-crystalline Bi nanowires below 50 nm exhibit semiconducting transport properties due to quantum confinement effect (QCE) [1], which takes an advantage of maximizing electric field effect. The gating effects are of great significance due to the enhancement of thermoelectric power (S) by positioning the Fermi energy (EF). In the present work, we report on the observation of the gate effects in an individual single-crystalline Bi nanowire at room-temperature.Single-crystalline Bi nanowires were grown onto an as-sputtered Bi thin film by heat treatment at 270 °C for 10 hours, resulting from thermal expansion mismatch between the film and a thermally oxidized Si substrate. The nanowires were dispersed onto a thermally oxidized silicon substrate with the underlying conducting Si used as a back gate. Electrical contacts to a nanowire among them were defined using a combination of photolithography and electron-beam lithography.The dependence of conductance on gate voltage was found in a field effect transistor (FET) based on an individual single-crystalline Bi nanowire with d = 120 nm, exhibiting three regions with different slopes of −4.5 × 10-9 μS/V (−50 ~ −35 V, region I), 3.2 × 10-9 μS/V (−35 ~ +35 V, region II), and 4.6 × 10-9 μS/V (+35 ~ +50 V, region III), respectively. The conductance of the FET decreases with increasing Vg (region I), and increases as Vg increases (region II). It is also found that the conductance rapidly increases after applying Vg over +35 V (region III), which means that Vg defining region II is symmetric. This is attributable to the unique property of Bi that the number of holes is equal to the number of electrons. The gate voltage induces an additional electron density ne = (ε0εSi02/ehSi02dBi)Vg [2], and, accordingly, elevates the position of the Fermi energy EF. Thus, the transition points at Vg = ± 35V of dG/dVg indicate that the pure hole (region I) and electron (region III) are the only carriers. This enables us to determine the carrier concentration of the individual 120-nm-diameter Bi nanowire, n ≈ 2.1 × 1017cm-3 at 300 K which is much lower than n of a bulk Bi, 2.73 × 1017cm-3 and 2.45 × 1018cm-3 at 4.2 and 300 K, respectively. The largest electron mobility μ (~ 4 × 105 cm2/Vs) and the longest mean free path l (~ 5 μm) were observed at room temperature, corroborating the high-quality crystalline of the Bi nanowire. Our results suggest that it is possible to control the electron doping level by positioning Fermi energy (EF), indicating the potential use in increasing thermoelectric power of single-crystalline Bi nanowires.References[1]. J. Heremans, C. M. Thrush, Y. Lin, S. Cronin, Z. Zhang, M. S. Dresselhaus, and J. F. Mansfield, Phys. Rev. B , 61, 2921 (2000).[2]. A. Boukai, K. Xu, and J. R. Heath, Adv. Mater. 18, 864 (2006)
Symposium Organizers
Wei Zhao University of Arkansas
Pehr E. Pehrsson Naval Research Laboratory
Stephen K. Doorn Los Alamos National Laboratory
Jie Liu Duke University
Phaedon Avouris IBM T. J. Watson Research Center
Symposium Support
Army Research Office
EE11: Electrical Properties and Electronics of Nanotubes and Nanowires III
Session Chairs
Thursday AM, April 12, 2007
Room 2016 (Moscone West)
9:00 AM - **EE11.1
Scanning Probe Studies of Minority Carrier Transport in Semiconductor Nanowire Devices.
Lincoln Lauhon 1
1 Materials Science and Engineering, Materials Research Center, Northwestern University, Evanston, Illinois, United States
Show Abstract9:30 AM - **EE11.2
Efficient Silicon Nanowire Thermoelectrics.
James Heath 1 , Akram Boukai 1 , Yuri Bunimovich 1
1 Chemistry, California Institute of Technology, Pasadena, California, United States
Show AbstractThermoelectrics offer the unique capabilities of power generation and refrigeration without the use of moving parts and toxic gases. Currently, thermoelectrics find limited use because of their poor efficiencies. However, recent theoretical work shows that nanoscale materials offer a way to increase the efficiency. In this talk, we will present studies on strained Silicon nanowires made using the Superlattice Nanowire Pattern Transfer (SNAP) method (Melosh, N.A. et.al., Science 300, 112 2003). SNAP allows us to control many important material parameters necessary for a highly efficient thermoelectric such as the doping, size, crystal orientation, etc. We measure the electrical conductivity, Seebeck coefficient, and thermal conductivity of our nanowires in order to calculate the efficiency. We will discuss the measured efficiencies of our nanowires and how they compare to state-of-the-art thermoelectric materials.
10:00 AM - EE11.3
High Performance Circuits Based On Ultra Dense Si NW Arrays.
B. Sheriff 1 , T. Karnik 2 , J. Heath 1
1 Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, United States, 2 Circuits Research Lab, Intel Corporation, Hillsboro, Oregon, United States
Show AbstractHigh performance circuits based on nanowire field-effect transistors (NW FETs) will require novel designs. These circuits will most likely be based on regular arrays of NW FETs to achieve the highest density and most consistent performance. However, due to the challenges and effort required to fabricate multiple NW FETs on one substrate, design parameters such as channel length, doping profiles, and contact materials have not yet been fully considered from a circuit perspective. As a consequence, these structures often are not optimized in terms of threshold voltage (VT) or circuit performance, which makes comparisons to CMOS difficult and often misleading. The realization of high performance circuits based on NW FETs is thus very challenging. Here, we present a methodology to optimize NW FET circuit performance by utilizing simulation software tools in the design process. This can be accomplished with two approaches. First, a look-up table of experimentally obtained I-V, G-V, and C-V values is constructed for a given device structure. The table is used as an empirical model by a circuit simulator to evaluate realistic circuit performance, which can be used to evaluate the merit of the NW FET design. Second, a device simulator is used to design high performance devices with optimized VT by varying parameters such as doping and gate materials. The simulated devices can also be used by the circuit simulator to predict circuit performance. This methodology is general for any novel device structure and mitigates the need to fabricate several prototypes in search for the optimized device structure. Data will be presented from fabricated NW FETs that utilize a dense array of doped Si NWs at 34 nm pitch as the channel material. From simulated results, several design changes can be implemented. For instance, our preliminary data show that significantly reducing the channel length and changing the gate dielectric material yields a factor of 3 improvement in inverter gain. The simulated and experimental results of initial and optimized structures will be reported. The simulated NW circuits will also be compared to conventional CMOS circuits.
10:15 AM - EE11.4
Transparent and Flexible Zinc Oxide Nanowire Network Transistors
Husnu Unalan 1 , Pritesh Hiralal 1 , Seung Cha 2 , Jae Jang 2 , Nalin Rupesinghe 1 , Y. Jin 2 , Gehan Amaratunga 1 , Jong Kim 1
1 Electrical Engineering Division, Engineering Dept., University of Cambridge, Cambridge United Kingdom, 2 , Samsung Advanced Institute of Technology, Suwon Korea (the Republic of)
Show AbstractZinc oxide (ZnO) nanowire networks provide a less lithographically intensive alternative to individual ZnO nanowire devices. Uniform and reproducible ZnO nanowire networks can be deposited over several centimeters, allowing fabrication of devices over large areas and they can be used as an alternative to organic and amorphous semiconductors for plastic electronics. In this work, we have deposited uniform ZnO networks using an easy, scalable, solution based method which was used for single walled carbon nanotubes [1]. Thin film transistors (TFTs) fabricated on flexible substrates (such as PET) which utilizes the ZnO nanowire networks as a channel between source and drain electrodes are presented. ZnO synthesis method and sheet resistance of the ZnO networks was found to be a critical factor in determining the device performance. Variation of device characteristics as a function doping, contact material and the channel length are given. Both bottom and top-gate transistors characteristics are presented.[1] H. E. Unalan, G. Fanchini, A. Kanwal, A.Du Pasquier, M. Chhowalla, Nano Lett. 6 (2006) 677.
10:30 AM - EE11.5
Low Frequency Noise of a Single Individual ZnO Nanowire and Multi-walled Carbon Nanotubes.
Kanghyun Kim 1 , Kangho Lee 1 , Haeyong Kang 2 , Byeong Yong Yoo 2 , Jung Il Lee 2 , Gyu-Tae Kim 1
1 School of Electrical engineering, Korea Univ., Seoul Korea (the Republic of), 2 , Korea Institute of Science and Technology, Seoul Korea (the Republic of)
Show Abstract10:45 AM - EE11.6
Versatile Metal Oxide Nanowire Devices Achieved via Controlled Doping.
Eric Dattoli 1 , Qing Wan 1 , Wei Lu 1
1 Electrical Engineering & Computer Science, University of Michigan, Ann Arbor, Michigan, United States
Show AbstractWe report for the first time in situ doping of transparent conducting SnO2 and In2O3 nanowires during vapor-liquid-solid growth. Optical transmittance and electrical transport measurements of degenerately tin doped indium-oxide (ITO) nanowires show that they are high-performance transparent metallic conductors with transmittance of about 85% in the visible range, resistivities as low as 6.29×10^(-5) Ω*cm and failure-current densities as high as 3.1×10^7 A/cm^2. Furthermore, to address the issue of the soaring cost and uncertain supply of indium in large scale applications, degenerately antimony doped tin-oxide (TAO) nanowires were synthesized and characterized, and were found to exhibit similar optical and electrical properties. Lateral field emission was observed from individual nanowires at room-temperature. Such metallic nanowires are ideally suited to function as large surface-area transparent electrodes, nanoscale interconnects and in point-electron source applications.In addition, lightly doped SnO2 nanowires were found to serve as the basis of adept FETs, with extracted carrier mobilities exceeding 100 cm^2/(V*s) and on-off ratios above 10^6. When configured as FETs, these nanowires provide increased drive current and greater environmental insensitivity as compared to undoped SnO2 nanowires. A new nanowire based device structure that will result in high-performance, fully transparent FET devices will also be discussed.
11:30 AM - **EE11.7
Sorting Single-Walled Carbon Nanotubes by Their Electronic Structure using Density Gradient Ultracentrifugation.
Mark Hersam 1
1 Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States
Show AbstractThe utilization of single-walled carbon nanotubes (SWNTs) in large quantities for molecular electronics, optoelectronics, biosensors, and medical applications will require SWNTs of the same physical structure, electronic type, and band gap. Since current methods of synthesis produce mixtures of nanotubes with different physical structures and electrical properties, the development of strategies for the post-production separation of these one-dimensional materials is highly desirable. In this work, we demonstrate a scalable method for separating SWNTs by their diameter and electronic type (i.e., semiconducting versus metallic) using density gradient ultracentrifugation (DGU). Since DGU is a technique commonly utilized to separate and isolate different sub-cellular components, DNA from RNA, and even different sequences of DNA by their compositions, we initially focused on the bulk sorting of DNA wrapped SWNTs in aqueous density gradients [1]. This process led to enrichment of SWNTs by diameter – especially in the small diameter regime (i.e., SWNT diameter = 0.7 – 1.0 nm). However, DNA wrapping possessed several undesirable characteristics including prohibitive expense in large scale production, irreversible wrapping, and inefficient wrapping for SWNTs with diameters exceeding 1 nm. Consequently, subsequent work has focused on DGU of surfactant encapsulated SWNTs [2]. In particular, bile salt surfactants, such as sodium cholate (SC), have overcome the drawbacks of DNA. Furthermore, additional control over the density-structure relationship has been achieved by using co-surfactant mixtures of SC and sodium dodecyl sulfate (SDS). For example, highly efficient metal versus semiconductor separation has been achieved with SDS:SC co-surfactant ratios ranging from 1:4 to 3:2. Characterization of the resulting sorted SWNT samples includes optical absorption spectroscopy, photoluminescence spectroscopy, atomic force microscopy, and direct charge transport measurements. Since DGU produces relatively large quantities of sorted SWNTs, this talk will conclude with our most recent efforts to realize enhanced performance in SWNT devices, such as thin-film field effect transistors, using SWNTs sorted by DGU.[1] M. S. Arnold, S. I. Stupp, and M. C. Hersam, "Enrichment of single-walled carbon nanotubes by diameter in density gradients," Nano Letters, 5, 713 (2005).[2] M. S. Arnold, A. A. Green, J. F. Hulvat, S. I. Stupp, and M. C. Hersam, "Sorting carbon nanotubes by electronic structure via density differentiation," Nature Nanotechnology, 1, 60 (2006).
12:00 PM - EE11.8
Nanoelectromechanical Pillar Operating as a Radio-frequency Mixer in the Nonlinear Regime.
Hyun Kim 1 , Hua Qin 1 , Robert Blick 1
1 Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States
Show Abstract12:15 PM - *EE11.9
Conduction mechanism of Aviram-Ratner rectifiers with single Pyridine-σ-C60 oligomers
Bing Wang 1 , Yunshen Zhou 1 , Xunlei Ding 1 , Jianguo Hou 1
1 HFNL, University of Science and Technology of China, Hefei, Anhui, China
Show AbstractThursday, April 12New Presentation Time and Paper Number*EE11.10 @ 11:30 to *EE11.9 @ 11:15 pmConduction mechanism of Aviram-Ratner rectifiers with single Pyridine-σ-C60 oligomers. Bing Wang
EE12: Photonics, Optics and Optoelectronics of Nanotubes and Nanowires
Session Chairs
Phaedon Avouris
Stephen Doorn
Pehr Pehrsson
Wei Zhao
Thursday PM, April 12, 2007
Room 2016 (Moscone West)
2:30 PM - **EE12.1
Optics and Optoelectronic of Carbon Nanotubes
Vasili Perebeinos 1
1 Watson Research Center, IBM - Watson, Yorktown Heights, New York, United States
Show AbstractCarbon nanotubes (CNTs) have remarkable optical properties due tothe electron-hole confinement in 1D, with important implications innanophotonics. The absorption spectra is dominated by excitons, withbinding energies and oscillator strengths described by the simplescaling relationships as a function of the tube chirality and thedielectric constant of the embedding material [1]. Theexciton-phonon interactions determines the fast decay of second E22exciton and leads to a phonon sideband signature 200-210 meV abovethe zero-phonon line, which provides a signature of the excitoniccharacter [2]. We calculate the exciton radiative lifetime, which inturn determines the efficiency of opto-electronic CNT devices. Wepredict an unusual nonmonotonic temperature dependence, due tooptically inactive "dark" exciton bands below the optically active"bright" exciton [3]. The field accelerated carriers can efficientlyproduce excitons via the impact excitation scattering mechanism,which produces locally high density of excitons giving rise to theultra bright nano light sources [4,5]. The electric field leads tothe exciton ionization, Stark shift of the exciton energy, andFranz-Keldysh oscillations in the absorption spectra.References[1] V. Perebeinos, J. Tersoff, and Ph. Avouris, Phys. Rev. Lett. 92,257402 (2004).[2] V. Perebeinos, J. Tersoff, and Ph. Avouris, Phys. Rev. Lett. 94,027402 (2005).[3] V. Perebeinos, J. Tersoff, and Ph. Avouris, Nano Letter 5, 2495(2005).[4] J. Chen, V. Perebeinos, M. Freitag, J. Tsang, Q. Fu, J. Liu, Ph.Avouris, Science, 310, 1171 (2005).[5] V. Perebeinos and Ph. Avouris, Phys. Rev. B, 74, 121410 (2006).
3:00 PM - **EE12.2
Advances in Nanowire Photonics.
Charles Lieber 1 2 , Fang Qian 1
1 Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States, 2 Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States
Show Abstract3:30 PM - EE12.3
CuIn(Ga)Se2 Nanowires for Solar Cell Applications
Yi Cui 1 , Hailin Peng 1
1 , Stanford University, Stanford, California, United States
Show AbstractI-III-VI semiconductors such as CuIn(Ga)Se2 (CIGS) have been actively studied for solar cell applications due to it high power efficiency of 19.2% in polycrystalline thin film, outperforming the best single crystalline devices. Here report the synthesis, characterization and applications of CIGS nanowires. CIGS nanowires are synthesized via a vapor-liquid-solid growth mechanism. The results on phase transformation, n- and p-type domain formation and their implications to solar cell devices will be discussed.
3:45 PM - EE12.4
Organic Light-emitting Diodes Having Carbon Nanotube Anodes.
Jianfeng Li 1 , Liangbing Hu 2 , George Gruner 2 , Tobin Marks 1
1 Chemistry Department, Northwestern University, Evanston, Illinois, United States, 2 Physics, University of California, Los Angeles, Los Angeles, California, United States
Show Abstract4:15 PM - EE12.5
Novel Phase Transformation and Pseudoelasticity in ZnO Nanowires.
Ambarish Kulkarni 1 , Kanoknan Sarasamak 2 , Sukit Limpijumnong 2 , Min Zhou 1
1 GWW School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States, 2 School of Physics, Suranaree University of Technology, Nakhon Ratchasima Thailand
Show AbstractWe report a novel pseudoelastic behavior resulting from a reversible phase transformation from wurtzite (WZ) to a novel graphite-like hexagonal (herein denoted as HX) structure in [01-10]-oriented ZnO nanowires under uniaxial loading. Molecular dynamics simulations are carried out to characterize this pseudoelastic response of nanowires with lateral dimensions of 18-41 Å over the temperature range of 100-700 K. Specifically, the size- and temperature-dependence of the critical stress for the initiation of the phase transformation, the recoverable strains associated with the pseudoelasticity, and the hysteretic energy dissipation are characterized. The large recoverable strains of 10-16% observed are unusual for the normally rather brittle ZnO ceramic and are due to both elastic stretch and the phase transformation in the slender one-dimensional nanowires. The hysteretic energy dissipation is between 0.05-0.14 GJm-3 per cycle and such low levels are attributed to the relatively low energy barrier for the transformation. First principles calculations show that this new polymorph corresponds to a distinct minimum on the enthalpy surfaces of ZnO under the conditions of the uniaxial tensile stress considered. The density functional theory calculations also reveal a relatively low transformation energy barrier of ~0.05 eV, providing an explanation for the small size of the hysteresis loop in the stress-strain relation and the low level of energy dissipation associated with the loading-unloading transformation cycle.
4:30 PM - EE12.6
TiO2 Nanowire Dye-Sensitized Solar Cells.
Janice Boercker 1 , Emil Enache-Pommer 1 , Eray Aydil 1
1 Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, United States
Show Abstract Nanowire-based photoanodes are being considered as an alternative to the mesoporous nanoparticle electrodes in dye-sensitized solar cells. It is presumed that faster electron transport in single crystal nanowires as compared to the electron recombination may allow more flexibility in design of dye sensitized solar cells. For example, optically thicker films may be realized to absorb more of the near infrared radiation where typical dye absorption is weak or electrolytes with lower redox potential but higher recombination rate can be tolerated. We synthesized TiO2 nanowires on titanium foils and used them as the wide band gap semiconductor photoanode in dye-sensitized solar cells (DSSC). The synthesis method takes advantage of the ability to grow sodium titanate (NaxH2-xTi3O7) nanowires through hydrothermal treatment of titanium metal in basic solutions. Specifically, the titanium foil was placed in a pressure vessel with 10 M NaOH and 35 wt% H2O2 and heated at 220 °C. A ~10 μm thick film of sodium titanate nanowires formed on the surface of the titanium foil after four hours. The sodium titanate nanowires were transformed, without loss of microstructure, to hydrogen titanate (H2Ti3O7) by exchanging the Na+ with H+ in 0.6 M HCl solution. The hydrogen titanate nanowires were converted to anatase TiO2 nanowires by heating them to 500 °C for 1 hour. X ray and electron diffraction confirmed that the nanowires were anatase TiO2. The nanowire morphology was preserved throughout the ion exchange and the annealing processes even though the crystal structure changed from monoclinic to tetragonal. High resolution transmission electron microscopy revealed that the nanowire axis is along the [101] direction. Solar cells were assembled by sandwiching the TiO2 nanowires between the Ti foil that they were grown on and a fluorine doped tin oxide (FTO) glass coated with a thin platinum layer. A ruthenium based organic dye cis-Di(thiocyanato)bis(2,2'- bipryidyl)-4-4’-dicarboxylate) ruthenium-(II) (N179) was absorbed onto the surface of the TiO2 nanowires. A liquid electrolyte containing the redox pair I-/I3- was injected in the space between the nanowires and the platinized FTO cathode. The typical preliminary TiO2 nanowire-based dye-sensitized solar cell exhibited short circuit currents of ~4 mA/cm2, open-circuit voltages of ~0.55 V with 60% fill factor and 1.3% overall efficiency under AM1.5 illumination. Intensity modulated photovoltage and photocurrent spectroscopies show that the transport rate through the nanowires is approximately three orders of magnitude faster than the electron loss rate by recombination.
4:45 PM - EE12.7
Transparent Conductive Carbon Nanotube Films for Organic Photovoltaic Cell Processing
Koungmin Ryu 1 , Cody Schlenker 2 , Daihua Zhang 1 , Xiaolei Liu 1 , Thomas Fijin 1 , Youngki Choe 1 , Mark Thompson 2 , Chongwu Zhou 1
1 Electrical Engineering, Univ. of Southern California, Los Angeles, California, United States, 2 Chemistry, Univ. of Southern California, Los Angeles, California, United States
Show AbstractWe have fabricated and optimized transparent conductive thin films made with commercially available arc-discharge single-walled carbon nanotubes. These films have been further exploited as hole-collecting electrodes to transport photogenerated charge carriers away from light-absorbing materials in photovoltaic cells on both rigid glass and flexible substrates. The optimized films show a typical sheet resistance of ~160 Ohm/square at 87% transparency. These films have been successfully used for the first time as electrodes for vapor-deposited organic multilayers to make photovoltaic cells with high stability and long lifetime. The performance is comparable to that of traditional photovoltaic cells based on indium tin oxide (ITO) films. Our experiments indicate that carbon nanotube films have high potential for future flexible organic solar cell applications.
5:00 PM - EE12.8
Electroluminescence of ZnO Nanowire/p-GaN Heterojunction Light Emitting Diodes.
Xinyu Wang 1 , Amir Dabiran 2 , Heiko Jacobs 1
1 Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota, United States, 2 , SVT Associates, Inc, Eden Prairie, Minnesota, United States
Show AbstractZnO nanowire/p-GaN heterojunction light emitting diodes (LEDs) were fabricated by growing ZnO nanowire vertical arrays in aqueous solution on Mg-doped p-GaN films. Diode-like, rectifying I-V characteristics were recorded at room temperature and a “current crowding” effect was observed due to the high sheet resistance of the GaN film. The majority of voltage drop was found to occur during current transport in the GaN film. Light emission centered at 390 nm and 585 nm was observed under forward bias while a broad emission centered at 520 nm was found under reverse bias. Two emission mechanisms have been explored: space charge limited current in the forward bias and tunneling in the reverse bias.
5:15 PM - EE12.9
Phase-Correlated Non-Directional Laser Emission from the End-Facets of a Semiconductor Nanowire.
Lambert van Vugt 1 , Sven Ruhle 1 , Daniël Vanmaekelbergh 1
1 Condensed Matter and Interfaces, Debye Institute, Utrecht University, P.O.Box 80000, 3508 TA Utrecht Netherlands
Show AbstractSemiconductor nanowires have attracted much interest recently due to their compelling optical properties such as sub-wavelength waveguiding
1,2, lasing
3 and enhanced strong light-matter interaction.
4 We grow ZnO wires of high crystal quality with diameters ranging from 20 to 500 nm, and a length of up to tens of micrometers. The length axis of the nanowires corresponds to the c-axis of the ZnO wurtzite crystal structure. The high crystal quality of the wires allows them to function as a 3D optical cavity in which optical modes are confined in three dimensions.We investigated the excitation-intensity dependent emission characteristics of individual ZnO nanowires of known geometry. Above the lasing threshold, the emission spectrum consists of several sharp peaks with energy spacings scaling with the inverse length of the nanowire; thus, the emission peaks correspond to longitudinal Fabry-Pérot modes of the nanowire cavity. Importantly, we observe a striking change of the image of the nanowire emission when increasing the excitation intensity above lasing threshold. Lasing nanowires exhibit an interference pattern which is due to coherent laser emission from the two wire end facets. Comparison with numerical simulations shows that the laser light is emitted nearly spherically from both end-facets with fixed phase difference.
5 This finding is of key importance for the construction of miniaturized lasers and photonic circuits from semiconductor nanowire building blocks.References
1 C. J. Barrelet, A. B. Greytak, and C. M. Lieber, Nanowire Photonic Circuit Elements, Nanoletters 4 (2004), p. 1981-1985.
2 M. Law, D. J. Sirbuly, J. C. Johnson, J. Goldberger, R. J. Saykally, and P. Yang, Nanoribbon Waveguides for Subwavelength Photonics Integration, Science 305 (2004), p. 1269-1273.
3 M. H. Huang, S. Mao, H. Feick, H. Yan, Y. Wu, H. Kind, E. Weber, R. Russo, and P. Yang, Room-Temperature Ultraviolet Nanowire Nanolasers, Science 292 (2001), p. 1897-1899.
4 L. K. v. Vugt, S. Rühle, P. Ravindran, H. C. Gerritsen, L. Kuipers, and D. Vanmaekelbergh, Exciton-Polaritons Confined in a ZnO Nanowire Cavity, Phys. Rev. Lett. 97 (2006), p. 147401.
5 L. K. v. Vugt, S. Rühle, and D. Vanmaekelbergh, Phase-correlated non-directional laser emission from ZnO nanowires, Nanoletters, in press (2006).Email:
[email protected]5:30 PM - EE12.10
New Insight on a Vertically Aligned Single-Walled Carbon Nanotube Film and an Application to All-Fiber Passive Mode-Locker
Shigeo Maruyama 1 , Yong-Won Song 2 , Erik Einarsson 1 , Shinji Yamashita 2
1 Department of Mechanical Engineering, The University of Tokyo, Tokyo Japan, 2 Department of Electronic Engineering, The University of Tokyo, Tokyo Japan
Show AbstractA new insight is gained on the structure of the vertically aligned single-wall carbon nanotubes (VA-SWNTs) [1-3] generated by alcohol catalytic CVD (ACCVD) technique [4]. The thickness-controlled growth of VA-SWNTs by using in-situ laser absorption method is now a routine [2]. Our recent finding of the simple removal method using hot-water [5] enabled us to transfer this film to various flat substrates for various applications. At the same time, transferring this film on transmission electron microscopy (TEM) grid made it possible to directly observe the morphology of nanotubes from the top. To our surprise, the average number of nanotubes of a bundle is less than about 10. Electronic properties measured by EELS and X-ray absorption revealed that nanotubes are virtually electronically isolated [6]. The saturable absorption functionality of SWNTs is well suited for the use in passively mode-locked lasers including ultrashort pulse formation with notable attractions including wide operating bandwidth ranging from 1 to 2 μm, ultra-short recovery time (~500 fs), high optical damage threshold, and excellent compatibility with fibers and nano-devices due to their extremely miniaturized foot print [7, 8]. Recently, we propose and demonstrate a novel all-fiber mode-locking scheme in which the evanescent field of the propagating light in the fiber interacts with the SWNTs to induce loss modulation in the laser cavity [9]. In this study, hot-water removed VA-SWNT film is attached onto a D-shaped fiber instead of the previously tried randomly sprayed SWNTs [9]. With this new configuration, each SWNT direction is aligned with the electric field of the evanescent field of guiding light. We successfully demonstrate the mode-locked laser. The pulsed output has 0.5 nm of spectral FWHM, and a 5.7 MHz repetition rate [10]. This new scheme highlights some remarkable advantages including (i) simple and safe SWNTs deposition process, (ii) maximized SWNTs interaction with the field of propagating light due to the SWNTs alignment, (iii) high (~100%) yield rate and reliability for the device manufacturing, and (iv) low SWNTs density threshold to achieve mode-locking. References:[1] Y. Murakami, et al., Chem. Phys. Lett. 385 (2004) 298.[2] S. Maruyama, et al., Chem. Phys. Lett. 403 (2005) 320.[3] Y. Murakami, et al., Phys. Rev. Lett. 94 (2005) 087402.[4] S. Maruyama, et al., Chem. Phys. Lett. 360 (2002) 229.[5] Y. Murakami & S. Maruyama, Chem. Phys. Lett. 422 (2006), 575.[6] E. Einarsson, Z. Zhang, H. Kataura, H. Shiozawa, T. Pichler, S. Maruyama to be submitted.[7] S. Y. Set, et al., J. on Select. Top. in Quantum Electron., Vol. 10, No. 1, pp. 137-146, 2004.[8] S. Yamashita, et al., Optics Lett., Vol.29, No.14, pp.1581-1583, 2004.[9] Y. W. Song, et al., OFC 2006, Paper OThQ3.[10] Y. W. Song et al, submitted to OFC 2007.
5:45 PM - EE12.11
Single-crystalline Branched Zinc Phosphide Nanostructures: Synthesis, Properties and Opotoelectronic Devices.
Rusen Yang 1 , Yu-Lun Chueh 1 2 , Jenny Morber 1 , Robert Snyde 1 , Li-Jen Chou 2 , Zhong Lin Wang 1
1 Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States, 2 Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu Taiwan
Show AbstractZn3P2 has many advantages as a novel optoelectronic material. It has a direct band gap of 1.4-1.6 eV, which is in the optimum range for solar conversion. Devices made from Zn3P2 can also greatly benefit from its large optical absorption coefficient and a long minority diffusion length. Further more, the constituent materials are abundant and cheap and would allow the large production of such devices as solar cell, infrared (IR) and ultraviolet (UV), sensors, lasers, and light polarization step indicators, etc. In addition, Zn3P2 exhibit distinct size quantization effect due to the large excitonic radii. However, current investigation on Zn3P2 are mainly limited to thin films, and very little has been done in the nanoscale range. In this paper, we have synthesized hierarchical tree-shaped nanostructures and nanobelts and nanowires of Zn3P2 in a thermal assisted laser ablation process [1, 2]. The morphology and crystal structure were examined with SEM, TEM and XRD, and the composition was confirmed by EDS. All nanostructures are tetragonal phased Zn3P2 with very good crystallinity. A strong absorption from ultraviolet to near infrared was revealed with optical measurement. Optical devices with high sensitivity and rapid response time were fabricated using individual Zn3P2 nanowires. Crossed heterojunction of an n-type ZnO nanowire and a p-type Zn3P2 nanowire has also been characterized and it offers a great potential for spatial resolvable high efficient photon detector.[1] R.S. Yang, Y.L. Chueh, J.R. Morber, L.J. Chou, Z.L. Wang, submitted. [2] http://www.nanoscience.gatech.edu/zlwang/
EE13: Poster Session: Photonics, Optics and Optoelectronics of Nanotubes and Nanowires
Session Chairs
Phaedon Avouris
Stephen Doorn
Jie Liu
Pehr Pehrsson
Wei Zhao
Friday AM, April 13, 2007
Salon Level (Marriott)
9:00 PM - EE13.1
Photoacoustic, Photoelectrochemical Current, and Ultrafast Carrier Dynamics Characterizations of TiO2 Electrodes Composed of Nanotubes and Nanowires Adsorbed with CdSe Quantum Dots.
Taro Toyoda 1
1 Department of Applied Physics and Chemistry, The University of Electro-Communications, Tokyo Japan
Show Abstract9:00 PM - EE13.11
Infrared Photodetectors from Electrodeposited InSb Nanowires.
M. Khan 1 3 , Xu Wang 2 , Xiaoye Jing 3 , Cengiz Ozkan 1
1 Mechanical Engineering, University of California Riverside, Riverside, California, United States, 3 Department of Electrical Engineering, University of California Riverside, Riverside, California, United States, 2 Department of Chemical and Environmental Engineering, University of California Riverside, Riverside, California, United States
Show AbstractInSb is well known for its direct narrow band gap (0.18 eV at 300 K) and various applications in electronic and optoelectronic devices with a very high electron mobility and ideal candidates for detector arrays operating in the infrared wavelength, high-speed electronic devices, and magnetoresistive sensors. In the past few years, there has been increasing interest in nanostructural III-V semiconducting materials due to their potential applications. However, although it is considered that the electrodeposition of high quality compound InSb with precise stoichiometry at ambient temperature from aqueous solutions is a challenge, it is surprising that only a few studies on this important issue has been reported. Beside films, Fabricating InSb nanowires and nanocables by simple electrodeposition in anodic alumina membrane has been reported. Transport properties along with thermal properties of InSb nanowires have been shown very recently. However, no attention has been given to the photoconducting properties of InSb nanowires despite the exciting possibilities for use in optoelectronic circuits or as infrared detectors. So far infrared detectors from InSb thin film p-n junctions have been reported. Here, according to the knowledge of the author for the first time we show the possibility of creating highly sensitive InSb nanowire photodetectors sensitive to infrared light by exploring the photoconducting properties of individual semiconductor nanowires as well as multiple nanowires.InSb nanowire arrays have been fabricated by direct current electrodeposition inside the nanochannels of anodic alumina membranes without subsequent annealing. After Au contacts were patterned to the nanowires using electron beam lithography, photoresponse studies were conducted. Absorbance peaks were also recorded from free suspending nanowires. A significant response was observed when the wires were exposed to visible light and infrared absorption peaks were observed during absorption experiment. The nanowires also showed a considerable photoresponse under varying light intensities. Comparisons were also made between single and multiple nanowires’ responses. Based on the observations of the absorbance peaks and the conductivity of the InSb nanowires here, we show the possibility of creating highly sensitive InSb nanowire detectors. In future the light-induced conductivity increase might allow to reversibly switching the nanowires between OFF and ON states for application in High Electron Mobility Transistors [HEMT].
9:00 PM - EE13.12
Metallized DNA Nanotemplates for the Fabrication of ZnO Nanostructures for Optoelectronic Applications
Xu Wang 1 , Fei Liu 2 , Kang Wang 3 , Cengiz Ozkan 4
1 Chemical Engineering, University of California, Riverside, Riverside, California, United States, 2 , IBM, New York, New York, United States, 3 , University of California, Los Angeles, Los Angeles, California, United States, 4 Mechanial Engieering, University of California, Riverside, Riverside, California, United States
Show AbstractDeoxyribonucleic acid (DNA)-based nanostructures have drawn a major attention in nanotechnology. In this study, aligned metallized-DNA strands are used as templates to fabricate ZnO nanowires and other nanostructures via chemical vapor deposition (CVD). Metal nanoparticles with positive charge along with lambda-deoxyribonucleic acid strands are utilized in synthesizing the nanotemplates. First,lamda DNA strands are immobilized and aligned in parallel arrays over silicon substrate via meniscus motion by controlled evaporation. Then, positively charged gold nanoparticles are selectively bound along the lamda DNA strands by electrostatic adsorption. Modulation of the zinc vapor/oxygen gas concentration in the CVD system is achieved via a spatial variation of the sample location inside the reactor tube. Characterization by scanning electron microscopy (SEM), X-ray diffraction (XRD), Photoluminescence spectrometer (PL), and conductivity measurements reveal that ZnO nanostructures possessing different morphologies, optical and electrical properties are obtained at different locations. Our studies form a step towards realistic applications of metallized oligonucleotide nanowires, and provide additional knowledge to fabricate tailored ZnO nanostructures for specific optoelectronic device applications.
9:00 PM - EE13.13
Optical Characterization of Er-doped Y2O3 Nanostructures.
Yuanbing Mao 1 , Jane Chang 1
1 Chemical and Biomolecular Engineering, University of California at Los Angeles, Los Angeles, California, United States
Show AbstractThere is continuing interest in trivalent rare earth ion-activated phosphors for a variety of applications including fiber-optic amplifiers, lasers, waveguides, X-ray imaging, bioimaging, field emission and electroluminescent displays due to their luminescent characteristics and stability. Yttrium sesquioxide is one of the typical phosphor materials for hosting trivalent rare earth ions. In fact, in our most recent study, we have developed a radical-enhanced atomic layer deposition process to control the spatial distribution of Er3+ ions in Y2O3 thin films with a concentration as high as 1021 cm-3, thereby achieving outstanding room temperature photoluminescence (PL) at 1.54 μm.1 Since nanocrystalline materials (e.g.: nanoparticles, nanowires, and nanotubes) often exhibit unique physical properties, such as increased luminescence efficiency, which are not observed with their bulk counterparts, in this study, we extended our investigation to a series of erbium doped yttrium sesquioxide nanostructures, which were prepared by a hydrothermal process following a dehydration reaction. Er-doped Y2O3 nanotubes and nanowires have been synthesized with varying erbium concentrations of 0-60 at.%, as confirmed by x-ray photoelectron spectroscopy. The as-synthesized nanostructures are single-crystalline, as determined by x-ray diffraction, and range from 50-300 nm in diameter and 2-10 μm in length. The erbium coordination number and local bonding environment are assessed by synchrotron based extended x-ray absorption fine structure analysis, and are shown to dictate the measured photoluminescence intensity.2,3 This investigation also allows us to determine which PL quenching process (e.g. ion immiscibility and ion-ion interaction) dominates in these nanostructures. These materials are thus promising for lasers and active waveguides in telecommunication application. References1. T.T. Van and J.P. Chang, “Controlled erbium incorporation and photoluminescence of Er-doped Y2O3”, Applied Physics Letters, 87, 011907 (2005).2. T.T. Van, J. R. Bargar, and J.P. Chang, “Er coordination in Y2O3 thin films studied by extended X-ray absorption fine structure”, Journal of Applied Physics, 100, 023115 (2006).3. T.T. Van, J. Hoang, R. Ostroumov, K. L. Wang, J. R. Bargar, J. Lu, H.-O. Blom, and J.P. Chang, “Nanostructure and temperature-dependent photoluminescence of Er-doped Y2O3 thin films for micro-optoelectronic integrated circuits”, Journal of Applied Physics, 100, 073512 (2006).
9:00 PM - EE13.3
Micro-Raman Spectroscopy of Wurtzite ZnO Nanowires and Nanocrystals.
Irene Calizo 1 , Manu Shamsa 1 , Sivashankar Krishnakumar 1 , Vladimir Fonoberov 1 , Alexander Balandin 1
1 Nano-Device Laboratory, Department of Electrical Engineering, University of California Riverside, Riverside, California, United States
Show AbstractZinc Oxide (ZnO) nanostructures, such as nanocrystals (NC) and nanowires (NW), continue to attract attention due to their proposed applications in optoelectronic devices [1]. Magnetically doped ZnO NC demonstrated potential for the room-temperature spintronic applications owing to their high Curie temperature for the transition to the ferromagnetic state. Phonons affect the optical response of semiconductor nanostructures and influence the spin coherence time. It is important to understand the modification of the phonon energies and dispersion in NC and NW structures. The wurtzite crystalline structure of ZnO leads to a more complicated phonon spectrum and its modifications even in relatively large NC. It was previously demonstrated theoretically that, while the frequency of polar optical phonons in zincblende NC is equal to that of the bulk crystal phonons, the polar optical phonons in wurtzite NC have a discrete spectrum of the frequencies different from those of the bulk crystal [2]. Raman spectroscopy has been widely used in order to study the optical phonon spectrum modification in NCs. In this presentation we report the results of the detail investigation of ZnO NC with the average diameter of 20 nm and ZnO NW with the diameters 20-70 nm. The investigated ZnO NC and NW have been characterized using the high-resolution TEM in order to verify the dimensions and quality of the nanostructures. The size of the considered nanostructures is such that one cannot expect strong phonon peak shifts due to the spatial confinement with the corresponding relaxation of the momentum conservation [3]. At the same time, the optical anisotropy of the wurtzite crystal combined with the dielectric constant discontinuity at the nanostructure boundaries result in the phonon spectrum modification as predicted by the theory for NC [2]. The detail analysis shows that the experimentally measured peaks in NW and NC are shifted as compared to their bulk positions. The observed phonon spectrum modification in ZnO nanostructures have been compared with the theoretical predictions. This work has been supported by the DARPA funded UCR-UCLA-UCSB Center for Nanoscience Innovation for Defense (CNID).[1] V.A. Fonoberov and A.A. Balandin, J. Nanoelectron. Optoelectron., 1, 19-38 (2006).[2] V.A. Fonoberov and A.A. Balandin, Phys. Rev. B, 70, 195410 (2004).[3] K. Alim, V.A. Fonoberov and A.A. Balandin, Appl. Phys. Lett., 86, 053103 (2005).
9:00 PM - EE13.4
Highly Ordered TiO2 Nanotube & Nanorod Arrays for Solar Cell Applications
Tae-Sik Kang 1 , Barney Taylor 1 , Michael Durstock 1
1 Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson AFB, Ohio, United States
Show AbstractIn using nanocrystalline materials for solar cell applications, charge recombination is one of the main problems due to a large number of grain boundaries and poor contact onto a current collecting electrode. Highly ordered TiO2 nanotube & nanorod arrays were synthesized by an alumina nanotemplating method. The diameter and length of the TiO2 nanostructured arrays can be controlled by varying the process parameters such as the aluminum anodization voltage and time. Uniformly sized nanostructures from 50 to 300 nm in diameter and from 5 to 20 μm in length can be grown over large areas with vertical alignment on a substrate. The nanostructures have the desired stoichiometric chemical composition and anatase crystal structure after firing at 450 oC for 1hr. The TiO2 nanostructured arrays were subsequently incorporated into dye-sensitized solar cells (DSSCs) using standard ruthenium dyes and the I-/I3- electrolyte system. The fabrication methodology as well as the results on device performance will be discussed.
9:00 PM - EE13.5
Electrical and Thermal Properties of Carbon Nanotube–Polymer Composite Materials
Enkeleda Dervishi 1 2 , Zhongrui Li 2 , Viney Saini 1 2 , Alexandru Biris 3 , Dan Lupu 3 , Steve Trigwell 4 , Alexandru Biris 2 1
1 Applied Science , University of Arkansas at Little Rock, Little Rock, Arkansas, United States, 2 Nanotechnology Center, University of Arkansas at Little Rock , Little Rock, Arkansas, United States, 3 , National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj Napoca Romania, 4 Electrostatic & Surface Physics Laboratory, Kennedy Space Center, Orlando, Florida, United States
Show AbstractNano-composite materials have been studied extensively because of their superior electrical and optical properties and large number of possible applications ranging from nano-electronics, special coatings, electromagnetic shielding, and sensors. This work is focused on the electrical and optical properties of carbon nanotubes (CNT)-polymer nanocomposite materials. The carbon nanostructures were analyzed by several analytical techniques, including Electronic Microscopy, Raman Spectroscopy, and X-Ray Photoelectron Spectroscopy. Carbon nanotubes were grown by catalytic chemical vapor deposition (CCVD) on metal/metal oxide catalytic systems using acetylene or other hydrocarbons. After the purification process, the nanotubes were functionalized with acid functional groups in order to achieve a good dispersion in water or other solvents. Raman Spectroscopy was used to analyze the CNT and CNT-polymer nanocomposite materials. The thermal and electrical properties of these CNT-polymer nanocomposite materials depend on the amount of CNTs in the polymer and also on the uniformity of the CNTs dispersed in the polymer. The uniformity of CNTs in the bulk and on the surface of the polymer is analyzed using Raman Spectroscopy. These results are correlated with the electrical and optical properties of the CNT-polymer nanocomposite films. A reduction in electrical resistivity was observed, as the nanotubes’ concentration in the polymeric films increased, while optical transparency remained 85 % or higher relative to acrylic films without nanotubes.
9:00 PM - EE13.6
Using Photochemistry in Molecular Crystal Nanostructures to Generate Reversible Micron-Scale Motions
Rabih Al-Kaysi 1 , Christopher Bardeen 1
1 Chemistry, University of California, Riverside, California, United States
Show AbstractWe have developed a general method of making nanorods composed of organic molecules by using Al2O3 nanoporous templates. Careful control of rod growth conditions leads to crystalline nanorods, in contrast to the amorphous nanowires and tubes generated by previous methods. These molecular crystal nanorods exhibit unique spectral and photochemical properties. For example, when crystalline nanorods composed of 9-tertbutyl-anthroate (9-TBAE) were irradiated with UV light they undergo a [4+4] solid-state photodimerization that resulted in a uniform 15% expansion along the rod axis. This is in contrast to random 9-TBAE crystals, which disintegrate under the same conditions. Transmission electron microscopy, atomic force microscopy, and comparison of the x-ray crystal structures of the monomer and photodimer all provide evidence for a mechanism based on a crystal-to-crystal photoreaction leading to an increase in molecular volume. It is likely that the high surface-to-volume ratio in the nanorods provides a strain relief pathway that is absent in larger crystals. In a similar approach, 200 nm diameter 9-Anthracene carboxylic acid (9-AC) crystalline nanorods were exposed to UV-light (greater than 300 nm), the resulting [4+4] photodimerization of the 9-AC molecules induces a shape change in the nanorod. Unlike the photodimerisation in 9-TBAE, this photodimerization is thermally reversible: the nanorods remain intact and revert back to their original shape after several minutes in the dark at room temperature. This photoinduced shape change of the 9-AC nanorods could be repeated without any apparent fatigue in the bending motion. We characterize the recovery kinetics, the photobleaching, and propose a molecular-level mechanism for the observed shape changes. Exposing micron-sized 9-AC crystals to similar illumination conditions causes cracking and fragmentation, even though the [4+4] photodimerisation is reversible in these crystals as well. These results suggest that crystalline organic nanostructures may provide a unique way to transform photochemical energy into mechanical motion on the nanometer scale.
9:00 PM - EE13.7
High Density, Vertically Aligned ZnO Nanorectifier Arrays at Low Temperature.
Sudip Batabyal 1 , Basudev Pradhan 1 , Amlan Pal 1
1 Dept. of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India
Show Abstract9:00 PM - EE13.9
Ultrahigh Sensitivity Zinc Oxide Nanowire UV Detectors.
Cesare Soci 1 , Arthur Zhang 1 , Bin Xiang 1 , Shadi Dayeh 1 , David Aplin 1 , Xinyu Bao 1 , YuHwa Lo 1 , Deli Wang 1
1 Department of Electrical and Computer Engineering, University of california, San Diego, La Jolla, California, United States
Show AbstractEE14: Poster Session: Sensors, Emitters and Structural Materials
Session Chairs
Phaedon Avouris
Stephen Doorn
Jie Liu
Pehr Pehrsson
Wei Zhao
Friday AM, April 13, 2007
Salon Level (Marriott)
9:00 PM - EE14.1
High Yield, High Sensitivity Aqueous Solution Ion Concentration Single-Walled Carbon Nanotubes Sensor Formed by Etching-Free Liquid Phase Deposition Silicon Oxide and Lift off Processes
Jeng-Hua Wei 1 , Ying-Ren Chen 1 , HorngJiunn Lin 1
1 Electronics Engineering, Ching Yun University, Jung-Li Taiwan
Show AbstractIn this paper, we were designed new devices structure and passivation method to fabricate an aqueous solution sensor using carbon nanotubes (CNTs) where the characteristic of the device was examined in aqueous solution ion concentration. In this devices, the single-walled carbon nanotubes were immersed in dimethylformamide (DMF) undergoing the ultrasound wave and spread between source and drain electrode on top of silicon oxide layer. Subsequently, top passivation insulator and sensor window of CNT sensor were from by a unique, selective grown Liquid Phase Deposition (LPD) silicon oxide and lift off processes. In CNT sensors, the passivated layer formed over the source and drain electrode, greatly suppressed the gate leakage current and the parasitical current flowed through the testing solution. In general, the passivation layer and sensor window were formed by the high temperature growth method and the following chemical/plasma etching process, these two processes will attack CNT itself then reduce the yield and sensitivity of CNT sensors. Used this LPD process and lift off process, first it avoided CNTs channel destroyed by the etched sensor window. Beside, the LPD is a water-based process and no residual solvent inside CNT will disturb the sensing process. In this report, we measured drain current for CNTs exposed to both the distilled water and aqueous solution (NaCl) under different gate bias. The noticeably different current was detected under fresh, water and aqueous solution cases. Furthermore, various aqueous solution concentrations were used and related drain current change was recorded. The above result demonstrated that the CNTFETs formed by selective LPD deposition plus lift off process had the capability for the highly sensitive ion/chemical/biological sensors.
9:00 PM - EE14.10
Carbon felt/ carbon nanotubes/Pani as pH sensor.
Marcelo Mulato 1 , Glaucio Silva 1 , Paola Corio 3 , Elaine Matsubara 2 , Jose Rosolen 2
1 Physics and Mathematics, University of São Paulo, Ribeirao Preto-SP, SP, Brazil, 3 , IQ-USP, Sao Paulo, SP, Brazil, 2 Chemistry, FFCLRP-USP, Ribeirão Preto, SP, Brazil
Show AbstractCarbon nanotubes (CNTs) have attracted considerable attention since their discovery in 1991 due to their unique structural, optical and electrical properties. Applications in nanoscience in very different areas are possible because of their special geometry and features. Potential applications of CNTs include composite, microelectronic devices, field emission materials, nanoelectronics device and sensors. Carbon nanotubes exhibit very good adsorption properties because they have high specific surface area and a nanoscale structure that provide a large number of sites for reactions, thus leading to a high sensitivity. This work proposes the composite carbon felt/carbon nanotube/Polyaniline as an alternative for application as a pH sensor device. The carbon felt/carbon nanotube is an electronic conductivity material and it was obtained from polymer felt (poliacrilonitrile felt) using oxidation and carbonization processes. The cup-stacked and bamboo-like tubes were grown on the fibers of carbon felt by chemical vapour decomposition method. The sensor was obtained by incorporating polyaniline on the nanotubes present on the fibers of carbon felt/carbon nanotubes composite. The measuring process uses an EGFET (Extended Gate Field Effect Transistors) configuration, which is a derivation of the ISFET (Ion Sensitive Field Effect Transistor) – that is basically a chemical semiconductor sensor. The drain-current versus source-drain voltage is presented for varying pH concentrations from 2 up to 12. The sensitivity of the sensor in the saturation region presents a linear response, as observed from pH values 2 to 12. The sensitivity is better than that reported for the use of zinc and tin oxides sensitive membranes, for instance. This shows the excellent properties of the film, which can even be improved for the future development of a new sensor, as will be discussed.
9:00 PM - EE14.11
Hydrogen Interaction with Polyaniline Nanofibers
Shabnam Virji 1 , Jesse Fowler 1 , Bruce Weiller 1
1 , The Aerospace Corporation, El Segundo, California, United States
Show Abstract9:00 PM - EE14.12
Carbon Nanotube-Based Fluid Flow Sensing
Chinung Ni 1 , Christian Deck 1 , Kenneth Vecchio 1 , Prabhakar Bandaru 1
1 Materials Science program, MEchanical Engineering department,, UC, San Diego, La Jolla, California, United States
Show Abstract9:00 PM - EE14.13
Fabrication and Functionalization of Composite Nanowires for Bimolecular Sensor.
Xu Wang 1 , Cengiz Ozkan 2
1 Chemical Engineering, University of California, Riverside, Riverside, California, United States, 2 Mechanical Engineering, University of California, Riverside, Riverside, California, United States
Show AbstractSemiconducting nanowires with three segments have been prepared using porous templates (AAO) as “molds”. The nanowires are composed of semiconductor-metal-semiconductor. The semiconductor is CdTe, and the metal is Au. The morphology of the composite nanowires was identified by SEM and HRTEM. The crystal structure of CdTe and Au were characterized by SAED. The dependence of the conductance on gate voltage made the composite nanowires field-effect transistors candidates. Cadmium telluride (CdTe) is one of the most important II–VI group compound semiconductors due to its interesting photoelectric properties. It has a direct energy band gap (1.4–1.5 eV), a relatively high optical absorption coefficient, and advanced photovoltaic properties, which make it suitable for fabricating photoelectron devices and solar cells. Gold does not have a stable surface oxide. Its surface can be cleaned simply by removing the physically and chemically adsorbed contaminants. It has been well studied that the bonding of the thiolate group to the gold surface is very strong. In our report, a single strand of DNA (PNA) with thiol group at the end was bound to the gold segment first. It acts as receptors for another strand of DNA. The molecular match between two complimentary strands of DNA could be reflected by the conductance variation. Therefore, the potential of the composite nanowires based bio-molecules sensor has been demonstrated.
9:00 PM - EE14.14
Integration of Nanowire Chemical Sensors with Micromachined Hotplates
PoChiang Chen 1 2 , Koungmin Ryu 1 2 , Ishikawa Fumiaki 1 2 , Daihua Zhang 2 , Chongwu Zhou 2
1 Material Science and Eng., Univ. of Southern California, Los Angeles, California, United States, 2 E.E. Electrophysics, Univ. of Southern California, Los Angeles, California, United States
Show Abstract Nanowire chemical sensors have attracted a lot of attention due to their small size and high surface-to-volume ratios. Our previous studies have shown that high performance chemical sensors based on indium oxide nanowires displayed a good detection of NO2 down to 5 ppb at room temperature. Operating these nanowire sensors at elevated temperatures may lead to even better performance and also enable the detection of other technologically important chemicals such as CO and ethanol. For the first time, we demonstrate the integration of nanowire chemical sensors with micromachined hotplates built on SiN membranes. This was achieved by wet etching of silicon wafers coated with SiN to produce suspended SiN membranes, followed by fabrication of the nanowire chemical sensors on top. A platinum electrode was patterned across the SiN membrane to work as the heater. These hotplates allowed nanowire chemical sensors to operate at elevated temperatures in order to enhance the sensitivity of chemical sensors to target gases. By applying different current through the platinum heating filament, we can easily vary the device temperature from room temperature to 450 degree Celsius. The detection limit of ethanol and CO was determined to be 1 ppm and 10 ppm at an operation temperature of 275 degree Celsius, respectively. This technique can be an important component for future “electronic nose” systems based on nanowire sensors.
9:00 PM - EE14.16
Processing, Microstructure & Mechanical Properties of Carbon Nanotube/Niobium-Reinforced Alumina Nanocomposites
K. Thomson 1 , D. Jiang 1 , S. Robertson 2 , R. Ritchie 2 , A. Mukherjee 1
1 Chemical Engineering & Materials Science, University of California, Davis, California, United States, 2 Materials Science & Engineering, University of California, Berkeley, California, United States
Show AbstractThe low density, chemical inertness, and high strength/hardness make ceramics a very promising candidate for structural and biomedical applications. However, utilization of ceramics for such load-bearing applications is impeded by their relatively low fracture toughness. The discussed research strives to improve the fracture toughness of alumina by incorporation of carbon nanotubes and/or niobium. These alumina nanocomposites were prepared using high-energy ball milling (HEBM) and consolidated via spark plasma sintering (SPS). In just a few minutes at 1200°C, fully consolidated nanocomposite samples were achieved. The nanocomposites’ microstructure was investigated via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Pulsed laser Raman spectroscopy verified the preservation of the intricate nanotube structure after SPS consolidation. Dispersion of carbon nanotubes within the nanocrystalline alumina was improved with use of an environmentally friendly organic surfactant. A variety of specimen configurations and mechanical testing methods were utilized to determine the material’s true fracture toughness. Incorporation of single-walled carbon nanotubes and niobium provided substantial improvement in the fracture toughness of pure alumina. Proposed toughening mechanisms and further research plans are discussed.
9:00 PM - EE14.17
ALD of Ta-based Adhesion Layers for CNT-Cu Matrix Composite Film Growth.
S. Menzel 1 , C. Hossbach 2 , J. Thomas 1 , M. Albert 2 , T. Gemming 1 , M. Stangl 1 , S. Hampel 1
1 , IFW Dresden, P.O. Box 270116, D-01171 Dresden Germany, 2 , Dresden University of Technology, Mommsenstr. 13, D-01069 Dresden Germany
Show Abstract9:00 PM - EE14.18
Doped Nanotubes Vanadium Oxide Macrocellular Foams: Integrative Chemistry toward Designing Lithium Batteries Positive Electrode.
Florent Carn 1 , Mathieu Morcrette 2 , Nathalie Steunou 4 , Cristine Surcin 2 , Bathelemy Desporte 1 , Jacques Livage 4 , Renal Backov 1
1 , CNRS-Universite Bordeaux-I, Pessac France, 2 , CNRS-Université de Picardie, Amiens France, 4 , CNRS-Université Pierre et Marie Curie, Paris France
Show AbstractIntegrative Chemistry is a new concept where fluid complexes and inorganic chemistry can be integrated to reach specific functionalities by the way of scissoring matter (soft and/or solid state) at various lengths scale with an aim of rational design.[1] In such context, designing new porous monolith-type materials involving hierarchical porosity and tailored macroscale shapes is an emerging area of technological interest toward heterogeneous catalysis, phase separations, artificial bone structure, thermal and/or acoustic insulation, ion-exchange operation, and so forth. Different patterns can be used at the macrosroscopic length scale as biliquid[2] or air-liquid foams.[3,4] Different inorganic polymers can be used toward specific applications mentioned above, among those, extensive interest is focused over vanadium oxides mainly for their structural and textural[5] diversity and potential applications in various domains as for instance, heterogeneous catalysis, cathode materials for advanced lithium batteries, visible light photochromism and electro-chromic devices.This study extends previous work[4] on the preparation of vanadium oxide foams using air-liquid bubbling process. In this issue, to create new advanced cathode devices dedicated for lithium batteries, carbon nanotubes have been added within the vanadium oxide macrocellular foam walls. Results will be discussed both in terms of interlayer distance parameters and carbon nanotubes percentages associated to the V2O5/Carbon nanotube composites. Charge-discharge cycling experiments and induced-capacities will be presented.[6] 1- R. Backov, Soft Matter, 2006, 2, 452.2- F. Carn, A. Colin, M.-F. Achard, H. Deleuze, E. Sellier, M. Birot, R. Backov, J. Mater. Chem., 2004, 14, 13703- F. Carn, P. Massé, S. Ravaine, H. Deleuze, C. Sanchez, B. Julian, D.R. Talham, R. Backov, Langmuir, 2006, 22, 5469.4- F. Carn, A. Colin, M.-F. Achard, H. Deleuze, C. Sanchez, R. Backov, Adv. Mater., 2005, 17, 62.5- F. Carn, N. Steunou , A. Colin, J. Livage, R. Backov Chem. Mater. 2005, 17, 644. 6- F. Carn, M. Morcrette, B. Desportes,C. Surcin, J.-M. Tarascon, N. Steunou, J. Livage, R. Backov, unpublished results.
9:00 PM - EE14.19
Gas Preconcentration, Separation And Detection With Carbon Nanotubes.
Michael Stadermann 1 , Aleksandr Noy 1 , Olgica Bakajin 1 , Vanessa Reid 2 , Adam McBrady 2 , Robert Synovec 2
1 Chemistry, Materials and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California, United States, 2 Department of Chemistry, University of Washington, Seattle, Washington, United States
Show AbstractSeparation and characterization of substances has been restricted to laboratory operations in the past, and the instruments performing the tasks are bulky and power-hungry. In today’s world, there is an increased demand for the capability of doing rapid separation and analysis of chemical substances in the field. This requires small, portable units that consume little power, but have the separation capacity of larger desktop systems. The key to reducing dimensions and power consumption lies in microfabrication, combined with the development of novel materials that can be used for separation.We are investigating the use of carbon nanotubes as gas preconcentrators, separators and detectors for portable detection systems. Their high surface-to-volume ratios make nanotubes an ideal adsorption phase for gas preconccentration, as well as a separation phase gas chromatography. Nanotubes can also be used to fabricate chemical-sensitive field effect transistors with parts-per-billion sensitivity. I will present our results with all three types of devices and show that nanotubes provide a promising alternative to existing technologies. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48 and supported by the DARPA Micro Gas Analyzers program.
9:00 PM - EE14.2
Freely Suspended Hybrid Nanotube Forests for Surface-Enhanced Raman Spectroscopy
Hyunhyub Ko 1 , Chaoyang Jiang 1 , Vladimir Tsukruk 1
1 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractWe describe the fabrication of freely suspended hybrid nanotube forests composed of polyelectrolyte multilayers and gold nanoparticles by using porous alumina membrane templates. Here, we introduce an evaporation-induced nanoparticle assembly inside the nanotube nanocapillaries, in which the internal nanostructures of the hybrid nanotube forests are controlled by changing the chemical functionalities and sizes of capillary pore and nanoparticles. We further investigate the SERS-based gas sensing on these hybrid nanotube forests with different internal nanostructures. The design of freely suspended nanotube forests is advantageous in the application of surface-enhanced Raman spectroscopy (SERS) for gas sensors due to its large surface area and tunable inter-nanotube gap.
9:00 PM - EE14.21
Improvement of Hydrogen Adsorption on Single-Walled Carbon Nanotubes and Activated Carbon.
Lyubov Lafi 1 , Richard Chahine 1 , Eric Poirier 1 , Pierre Benard 1
1 Hydrogen Research Institute, Université du Québec à Trois-Rivières, Trois-Rivières, Quebec, Canada
Show Abstract9:00 PM - EE14.23
Molecular Dynamics Simulations of Hypersonic Velocity Impact Protection in Carbon Nanotube Reinforced a-SiC Composites
Maxim Makeev 1 , Deepak Srivastava 1
1 , NASA Ames Research Center, Moffett Field, California, United States
Show Abstract9:00 PM - EE14.25
Improved Field Emission Properties of Thiolated Carbon Nanotubes on Carbon Cloth.
Pai-Yen Chen 1 , Fang-Tzu Chuang 2 , Tsung-Chieh Cheng 1
1 , National Nano Device Laboratories, Hsinchu Taiwan, 2 Material Science and Engineering, National Chiao- Tung University , Hsinchu Taiwan
Show Abstract9:00 PM - EE14.26
Field Emission Properties of Large Area Carbon Nanotube Cathode in Different Electric Field Mode.
Qingliang Liao 1 , Yue Zhang 1 2 , Liansheng Xia 3 , Yunhua Huang 1 , Zhanjun Gao 1 , Junjie Qi 1 , Ruiping Gao 4 , Kexin Chen 4
1 Department of Materials Physics, University of Science and Technology Beijing, Beijing, Beijing, China, 2 State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing, Beijing, China, 3 Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang, Sichuan, China, 4 , National Natural Science Foundation of China, Beijing, Beijing, China
Show Abstract9:00 PM - EE14.27
Stable Multi-Wall Carbon Nanotube Field Emission Electron Microscope operating in Low Vacuum
Hiroshi Suga 2 1 , Teruaki Ohno 3 , Miyuki Tanaka 1 , Hiroshi Tokumoto 4 , Yasushiro Nishioka 2 , Tetsuo Shimizu 1
2 , Nihon Univ., Funabashi Japan, 1 NRI, AIST, Tsukuba Japan, 3 , Technex Lab., Machida Japan, 4 , Hokkaido Univ., Sapporo Japan
Show Abstract To develop a new electron emitter which can operate at low extraction voltage in 10-3 Pa, we fabricated an individual multi-wall carbon nanotube (CNT) field emitter and investigated its emission properties. Although the emission current reached 1.0μA at 70V and indicated linear behavior in Fowler-Nordheim (F-N) plots, its current fluctuation and lifetime were more than 30% and less than 5 hours, respectively. Before and after field emission experiments, changes in CNT length were observed, indicating CNT evaporation. This clearly demonstrated that it is necessary to develop a new way to realize long-time stable electron emission. Then we tried inserting high ohmic resistance between the electron emitter and the power supply. As a result, the current fluctuation decreased from 30% to 2% at 0.1 μA, and the lifetime increased from 5 to 50 hours. Hence, insertion of high resistance is quite effective for a long-time stable CNT emitter. Finally, to show the effectiveness of this procedure, we constructed an actual field emission scanning electron microscope (FESEM) optimized for a CNT emitter and took a stable FESEM image with a resolution of 30nm. Further we have investigated the influence of introduced gases on the electron emission properties. We believe that a new electron microscope equipped with a CNT emitter such as our CNT-FESEM will be developed in the near future.
9:00 PM - EE14.28
Fabrication of Reliable Individual Carbon Nanotube Field Emitters for Applications as Electron Beam Sources
Bryan Ribaya 1 3 , Joseph Leung 2 , Philip Brown 4 , Mahmud Rahman 3 , Cattien Nguyen 1 3
1 , ELORET/NASA Ames Research Center, Moffett Field, California, United States, 3 Electrical Engineering, Santa Clara University, Santa Clara, California, United States, 2 , NASA Ames Research Center, Moffett Field, California, United States, 4 , Union College, Schenectady, New York, United States
Show AbstractIndividual carbon nanotube cold field emitters are promising point electron sources because of their low energy spread, high brightness, and low power consumption [1,2]. Potential applications for such efficient electron sources include advanced miniaturized electron microscopy and portable X-ray tube. Precision fabrication and integration of nanoscale structures to macroscale has been a general and grand challenge to realizing nanotechnology. In this paper, we present a novel fabrication technique for individual carbon nanotube field emission cathodes based on Si MEMS structures [3]. Individual nanotube is attached to Ni-coated Si microstructure and as such the individual nanotube structure may be readily integrated to micro- and macrosale systems utilizing MEMS technology. The MEMS carbon nanotube cathode structures are interrogated for their mechanical and electrical reliability. We discover that a 25-nm nickel coating yields reliable electrical and mechanical cathode devices, affording reproducible field emission behavior. The current-voltage data will be presented for elucidation of electrical properties of the nanotube-MEMS structure interface. Definitive field emission data from an individual carbon nanotube will also be presented for the new Si-based cathode structure. Reproducible and stable emission current greater than 200 nA for individual nanotube emitter is achieved, thus demonstrating the feasibility of this device for application as electron point source for advanced scanning electron microscopy. Novel cathode structures composed of two parallel MWNTs are demonstrated using this technique, with the lengths and interspatial separation of the CNTs precisely controlled. These novel CNT cold cathode structures provide opportunities for future fundamental investigations into the nature of carbon nanotube emitters as well as provide a feasible pathway for precise macro-scale integration of CNT emitters for applications.1.B. Ribaya, D. Niemann, N. Gunther, M. Rahman, C. V. Nguyen, Proc. IVEC/ IVESC, pp. 25-3-4, (2006).2.N. de Jonge and J.-M. Bonard, Phil. Trans. R. Soc. Lond. A 362, 2239 (2004).3.B. P. Ribaya, J. Leung, P. Brown, M. Rahman, C. V. Nguyen, In Preparation (2006).
9:00 PM - EE14.29
Patterned Carbon-nanotube Field-emitter Arrays: A Study of Pattern Dimensions and Growth Conditions.
Andrew Monica 1 , Stergios Papadakis 1 , Robert Osiander 1
1 , Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, United States
Show Abstract9:00 PM - EE14.3
The Dielectrophoresis Aligned Ni Silicide Nanowire as a Microscopy Tip
Joondong Kim 1 , Young-Hyun Shin 1 , Jin-Won Song 1 , Hee Won Seo 1 , Eung-Sug Lee 1 , Wayne Anderson 2 , Chang-Soo Han 1
1 , Korea Institute of Machinery & Materials, Daejeon Korea (the Republic of), 2 Electrical Engineering, University at Buffalo, State University of New York, Buffalo, New York, United States
Show Abstract Beyond the growth or fabrication of nanomaterials, such as nanotubes, nanowires, or nanoparticles, there is a need to achieve nanoscale functional devices. The inevitably essential process is to place the nanostructure in the desired place, which may also contribute to simplify the fabrication procedures as well as to reduce the cost. The Dielectrophoresis assembly method was used to align a Nickel (Ni) silicide nanowire onto a microscopy tip. Single crystalline Ni silicide nanowires, grown by the metal-induced method1,2, were collected from a substrate and dispersed in the methanol solution then dropped on the AC electric field (5 – 10 V, 5 MHz) applied space between microscopy tip and a metal electrode to be aligned. The probe tip had 0.5 – 1 µm in length and 20 – 40 nm in diameter and provided a clear spatial resolution. The dielectrophoresis aided Ni silicide nanowire alignment is simple and highly repeatable to satisfy the industrial requirements. The metallic Ni silicide nanowire is a promising nanoscale entity in electric force microscopy application due to the low resistance metallic property. We discuss the Ni silicide attached microscopy tip fabrication as well as the practical uses. References[1] J. Kim and W. A. Anderson, Nano Lett. 6, 1356 (2006). [2] J. Kim and W. A. Anderson, Appl. Phys. Lett. 86, 253101 (2005).
9:00 PM - EE14.30
Demonstration of a Microfabricated Carbon Nanotube Ionization Source.
Srividya Natarajan 1 2 , Christopher Bower 2 , Jeffrey Piascik 2 , Brian Stoner 2 , Charles Parker 1 , Scott Wolter 1 , Jeffrey Glass 1
1 Electrical and Computer Engineering, Duke University, Durham, North Carolina, United States, 2 , RTI International, Durham, North Carolina, United States
Show AbstractMass spectrometry is widely used to identify compounds and understand their chemical composition. Its applications range from medical and space research to forensics. For effective operation, the mean-free path of the analyte gas should be greater than the characteristic length of the mass spectrometer. Miniaturizing a mass spectrometer would allow analyte detection in a smaller volume, permitting a shorter mean free path for the analyte gas. For example, a device with characteristic length on the order of 0.1 to 1 cm, would allow operating pressures to be in the 10 to 100 mTorr range, without compromising accuracy. Other advantages of such a device would include portability and lower power consumption. The ionization source is a critical component of a mass spectrometer and this study focuses on demonstrating a low power, miniaturized ionization source. The field emission properties of carbon nanotubes along with microfabrication and micro-electro-mechanical systems (MEMS) processing methodology are used to achieve this objective. The present study builds upon the work of C. Bower and co-workers who have demonstrated an on-chip microtriode using carbon nanotube field emitters [1]. The MEMS design used to construct the ion source allows lateral construction of the electrodes on a silicon surface. Once the sacrificial oxide is etched away, vertically aligned multi-walled carbon nanotubes (MWNTs) are selectively deposited on the desired electrode using microwave plasma-enhanced chemical vapor deposition (MPCVD). Subsequently, the electrode panels are rotated and locked in place normal to the substrate. The turn-on fields (i.e., the field needed to obtain a current of 1 nA) for the MWNT films are in the 10 V/μm range. A hydrogen plasma treatment is found to lower the turn-on fields to 5 – 7 V/μm. Electrons emitted from the carbon nanotubes are accelerated through suitable potentials at the electrodes to provide them with desirable energies for ionization via electron impact ionization. The electron and ion currents were measured as a function of pressure for various gases. Ion currents for helium, argon, nitrogen and xenon, as a function of pressure, will be presented. The ion currents ranged from pA to μA in the 0.1 to 100 mTorr pressure range. To our knowledge, this is the first controllable ion source of this scale and can function as a miniature pressure sensor or as the ion source for a miniature mass spectrometer. 1.C. Bower, W. Zhu, D. Shalom, D. Lopez, L. H. Chen, P. L. Gammel, and S. Jin, Appl. Phys. Lett., 80, 3820 (2002).
9:00 PM - EE14.31
Uniform Carbon Nanotube Films with High Field Emission Currents Fabricated Using Small Organic Molecules as Surfactants
Lei An 1 , Otto Zhou 1
1 Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina, United States
Show Abstract1- pyrenemethyl amine hydrochloride and a Naphthalene derivative have been used as surfactants to uniformly dissolve carbon nanotubes into alcohol solutions. These carbon nanotube alcohol solutions can be readily used for electrophoretic deposition to deposit carbon nanotubes onto silicon substrates in order to fabricate uniform nanotube films that would display high field emission currents. Experimental data have shown that these surfactants have helped carbon nanotubes distributed uniformly in solution, which is a prerequisite for fabricating uniform nanotube films for field emission purpose. These small organic molecules would decompose during the annealing process so the surface of carbon nanotubes would not be contaminated. As a result, uniform carbon nanotube films with high field emission currents were obtained.
9:00 PM - EE14.32
Efficient and Long-lifetime Field Emission from Individual Carbon Nanotube Pillar Bundles
Shunjiro Fujii 1 , Shin-ichi Honda 1 , Hideyasu Kawai 1 , Kazuhiro Ishida 1 , Hiroshi Furuta 2 , Takashi Hirao 2 , Kenjiro Oura 3 , Mitsuhiro Katayama 1
1 Dept. of Electronic Eng., Grad. Sch. of Eng., Osaka Univ., Osaka Japan, 2 Dept. of Electronic and Photonic Systems Eng., Grad. Sch. of Eng., Kochi Univ. of Tech., Kochi Japan, 3 , Research Center for UHVEM, Osaka Univ., Osaka Japan
Show AbstractCarbon nanotube (CNT) is expected to be an ideal material for use as field emitters in field emission displays (FEDs) due to its intriguing properties such as small radii of curvatures at the tip apex, excellent electrical conductivity and chemical inertness. Regarding an aligned CNT array as a field emitter, it is important to control the length and the intertube distance of CNTs to reduce the screening effect in adjacent CNTs. Recently, by using pillars of aligned CNT bundles, we have succeeded in fabricating an architecture that satisfies the optimal ratio of interpillar distance (R) to pillar height (H), which showed highly efficient field emission.[1] However, the detailed mechanisms of the enhanced filed emission from CNT pillar bundles and its long-term field emission durability required for device application have not been investigated. In this study, we investigated the field emission mechanism from individual aligned carbon nanotube pillar bundles. The pillars of vertically aligned CNT bundles were synthesized by thermal chemical vapor deposition (CVD). Patterns of the Fe/Al multilayer catalysts were fabricated on a stainless steel substrate. The thermal CVD was carried out at a growth temperature of 650°C under a pressure of 600 Pa maintained by flowing acetylene (C2H2) and helium (He) gases. A scanning electron microscopy (SEM) image showed that an individual pillar of aligned CNT bundles with a diameter of 50 μm and a height of 70 μm was aligned perpendicular to the substrate surface. The field emission properties were measured using parallel plates with a 1 mm separation in a high-vacuum system (base pressure: 10-7 Pa). The threshold electric field, Eth, needed to produce a current density of 10 mA/cm2, was 2.0 V/μm. Over the Eth, no current saturation was observed, and the current density of field emission reached as high as 2.8 A/cm2 at 2.9 V/μm. From a calculation on electric field distribution, it was found that the electric field was significantly high at the edge of the pillar bundle compared with that at the center, indicating that the excellent field emission properties of the aligned pillar bundles were attributed to the edge effect. The time dependence of the emission current density was also measured in high-vacuum. During 200 h of continuous current emission of 150 mA/cm2 at a DC electric field of 2.4 V/μm, no obvious degradation in current density was observed. It is likely that since the current per single CNT is low due to its high-density structure, the pillar bundles showed a good lifetime property even at high current density. [1]M. Katayama, K. -Y. Lee, S. Honda, T. Hirao, and K. Oura, Jpn. J. Appl. Phys. 43, L774 (2004).
9:00 PM - EE14.34
Vertically Aligned CNTs Embedded in Cr/TiO2 Membranes for the Realization of Ion Sources.
Yaser Abdi 1 , Shams Mohajerzadeh 1 , Javad Koohsorkhi 1 , Bahman Hekmatshoar 1
1 Electrical and Computer Eng., University of Tehran, Tehran, -, Iran (the Islamic Republic of)
Show Abstract9:00 PM - EE14.4
Characterization of Single-walled Carbon Nanotube Network Gas Sensor under a High-vacuum Environment.
Winadda Wongwiriyapan 1 , Shin-ichi Honda 1 , Takafumi Ohmori 1 , Satoshi Inoue 1 , Tatsuya Ito 2 , Ryotatro Shimazaki 2 , Toru Maekawa 2 , Kengo Suzuki 2 , Hiroshi Ishikawa 2 , Kenjiro Oura 3 , Mitsuhiro Katayama 1
1 Division of Electrical, Electronic and Information Engineering, Osaka University, Osaka Japan, 2 , New Cosmos Electric Co., Ltd, Osaka Japan, 3 Research Center for Ultrahigh Voltage Electron Microscopy, Osaka University, Osaka Japan
Show Abstract9:00 PM - EE14.5
Gas Pressure Sensor Based on PECVD Grown Carbon Nanotubes.
Richard Ficek 2 , Lenka Zajickova 1 , Marek Elias 1 , Ondrej Jasek 1 , Frantisek Matejka 3 , Radimir Vrba 2
2 Faculty of Electrical Engineering and Communication, Technical University, Brno Czech Republic, 1 Department of Physical Electronics, Masaryk University, Brno Czech Republic, 3 , Institute of Scientific Instruments, Brno Czech Republic
Show Abstract9:00 PM - EE14.6
Environment-responsive Single-walled Carbon Nanotube Dispersion.
Dan Wang 1 , Liwei Chen 1
1 Chemistry & Biochemistry, Ohio University, Athens, Ohio, United States
Show Abstract9:00 PM - EE14.7
Mechanical Resonance of Clamped Silicon Nanowires Measured by Optical Interferometry.
Miro Belov 1 2 , Nathaniel Quitoriano 3 , Shashank Sharma 3 , Ted Kamins 3 , Stephane Evoy 1 2
1 Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada, 2 , National Institute for Nanotechnology, Edmonton, Alberta, Canada, 3 Quantum Science Research, Hewlett-Packard Laboratories, Palo Alto, California, United States
Show AbstractResonant cantilevers have been proposed as highly-sensitive transducers for the detection and assaying of molecular systems. Surface machining now routinely allows the fabrication of mechanical objects with lateral dimensions reaching the sub-100 nm range and resonant frequencies in the GHz range. However, typical surface machining procedures employed in NEMS fabrication are inherently slow and offer limited yield. In addition, these procedures usually employ plasma-assisted etching techniques that may introduce surface damage and significantly degrade the mechanical properties of the resonating element. Alternatively, the direct growth of cantilevered nanowires by chemical vapor deposition methods offers a potent alternative for the efficient production of high-quality NEMS resonators, conceivably also allowing access to device dimensions reaching the 20 nm range. We report the synthesis and characterization of mechanically vibrating silicon nanowires grown by chemical vapor deposition. These highly-oriented and clamped silicon structures were laterally grown from the sides of etched silicon posts using a metal-catalyzed chemical vapor deposition process. The diameters and lengths of the structures ranged from D = 20 to 270 nm and from L = 2 to 30 um, respectively. The substrates were mounted onto a piezoceramic disc and installed in a vacuum cryostat. The tracking output of a spectrum analyzer provided a driving signal to the piezoelectric disc. The substrates were actuated at varying frequencies until the mechanical resonance of the suspended wires was observed by optical interferometry. Such data was acquired at temperatures ranging from T = 77K up to 293K, and at pressures ranging from atmospheric down to the low 10^-6 Torr range. Typical resonant frequencies ranged from f = 1 to 20 MHz, in agreement with the Euler-Bernoulli analysis of the structures. The resonant frequency of the nanowires typically showed a 0.25 % increase as the nanowires were cooled from T = 293 K to T = 77 K. The qualities of the resonances also decreased from Q = 5000 to Q = 2500 over the same temperature range. We will also discuss surface-related energy dissipation processes and other aspects of our experimental approach, including the actuation and assaying of the nanoresonators at ambient pressures.This work was partially supported by Alberta Innovation and Science and by Hewlett-Packard Laboratories.
9:00 PM - EE14.8
Effects of Ag+ on the Redox Chemistry of ssDNA-Encased HiPco Carbon Nanotubes with Hydrogen Peroxide.
Xiaomin Tu 1 , Wei Zhao 1
1 Department of Chemistry, University of Arkansas, Little Rock, Arkansas, United States
Show AbstractThe investigation of solution redox chemistry of single-walled carbon nanotubes (SWNTs) has been an area of great interest. Our previous studies have found that single-stranded DNA (ssDNA) wrapped SWNTs are optically sensitive to H2O2, which makes them ideal candidates in sensor applications. In order to fully understand the redox chemistry of SWNTs with H2O2, we systematically investigate the effect of buffer constituents and the role of metal ions on the reaction. It has been discovered that Ag+ can be reduced to Ag nanoparticles on the surface of DNA-SWNTs upon light irradiation. Such a nanoparticle/nanotube hybrid may afford new applications of SWNTs. Here, we have incorporated Ag+ into the H2O2 reacting ssDNA-SWNT systems. Two types of SWNT samples were used here, pre-HPLC purified ssDNA-SWNT sample and HPLC purifed ssDNA-SWNT sample. Under room light exposure, the addition of Ag+ in pre-HPLC purified ssDNA-SWNT samples containing H2O2 causes the near infrared spectral intensity of the S11 bands to decrease initially. Then the suppressed spectral intensity restores over time. A plasmon band of Ag nanoparticles at about 420 nm is observed. On the other hand, under the same condition, the addition of Ag+ into the HPLC purified ssDNA-SWNT samples facilitates the reaction of SWNTs with H2O2 and no spectral restoration is observed. In addition, the concentration of Ag nanoparticles produced from ssDNA-SWNT suspensions is almost 5 times as higher as that of a control containing no SWNTs, which confirms SWNT catalytic effect on the reduction of Ag+ to form Ag nanoparticles. The rich solution chemistry of SWNTs shows great promise for applications.
9:00 PM - EE14.9
Hydrogen Sensing Properties of Pd Single Nanowires Fabricated by Electron-beam Lithography
Eunsongyi Lee 1 , Minhong Jeun 1 , Wooyoung Lee 1
1 , Yonsei University , Seoul Korea (the Republic of)
Show Abstract
Symposium Organizers
Wei Zhao University of Arkansas
Pehr E. Pehrsson Naval Research Laboratory
Stephen K. Doorn Los Alamos National Laboratory
Jie Liu Duke University
Phaedon Avouris IBM T. J. Watson Research Center
Symposium Support
Army Research Office
EE15: Sensors, Emitters and Structural Materials
Session Chairs
Friday AM, April 13, 2007
Room 2016 (Moscone West)
9:00 AM - **EE15.1
Influence of Redox Molecules on the Electronic Cnductance of Single-walled Carbon nanotubes: Application to DNA Sensing.
Bruce Diner 1 , Salah Boussaad 1 , Xueping Jiang 1 , Janine Fan 1 , Kristin Ruebling-Jass 1
1 CR&D, E. I. du Pont de Nemours & Co., Wilmington, Delaware, United States
Show Abstract9:30 AM - **EE15.2
Trace Chemical Detection Using Single-Walled Carbon Nanotubes
Eric Snow 1 , Joshua Robinson 1 , Keith Perkins 1 , Mike Papantonakis 1 , Jennifer Stepnowski 1 , Duane Simonson 1 , Andy McGill 1
1 , Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractIn this presentation I will report on our effort to develop a system for detecting and identifying trace levels of chemical vapors that is based on a single-walled carbon nanotube (SWNT) sensor technology. The sensor detects the change in capacitance and/or conductance of a random network of SWNTs. The SWNT sensor is inexpensive to manufacture, fast (< 1 s), sensitive (sub-ppb), completely reversible, and has an extremely large dynamic range. The detection system consists of SWNT sensors coupled to a micromachined front-end vapor delivery system that is designed to provide additional gain and chemical specificity. This detection system will be compact, low power, and capable of rapidly detecting and identifying trace levels of explosives and chemical warfare agents at concentrations below 100 parts per trillion.
10:00 AM - EE15.3
Fluorescein as a Simultaneous Noncovalent Anchor and Fluorescent Marker of Single-walled Carbon Nanotubes.
Sarunya Bangsaruntip 1 , Nozomi Nakayama-Ratchford 1 , Xiaoming Sun 1 , Hongjie Dai 1
1 Department of Chemistry, Stanford University, Stanford, California, United States
Show Abstract10:15 AM - EE15.4
Supported Lipid Bilayer/Carbon Nanotube Hybrids.
Xinjian Zhou 1 , Jose Moran-Mirabal 2 , Harold Craighead 2 , Paul McEuen 1
1 Physics, Cornell University, Ithaca, New York, United States, 2 Applied and Engineering Physics, Cornell University, Ithaca, New York, United States
Show AbstractSingle-walled carbon nanotubes (SWNTs) offer unique opportunities for chemical and biological sensing. SWNT transistors have mobilities that exceed those of silicon and have transverse dimensions comparable to a strand of DNA. They also work efficiently in aqueous environments and, unlike silicon-based biosensors, they do not require an insulating layer to separate the ions from the conducting channel. An exciting possibility is to use a nanotube to probe the properties of lipid membranes and their functional constituents. Supported lipid bilayers (SLBs) self-assemble from phospholipids on flat, hydrophilic substrates like glass, and mimic many properties of cell membranes. The lipids in a SLB are laterally mobile and many reconstituted membrane proteins embedded in them remain functional. Here, we show the integration of SLBs with SWNT field effect transistors (FETs). We first demonstrate membrane continuity and lipid diffusion over the tube. The NT acts as a diffusion barrier for a membrane-bound tetanus toxin protein, and the strength of the diffusion barrier depends on the diameter of the NT. Finally, we present results on the electrical detection of specific binding of streptavidin to biotinylated lipids.
10:30 AM - EE15.5
CNT Uptake in Human Ovarian Cancer Cells: Changes in Fluorescence Emission of CNT-Fluorescein in SKOV-3 Ovarian Cancer Cells
Meng-Tse Chen 1 , Lewis Arco 2 , Yinghua Sun 1 , P. Thomas Vernier 3 4 , Fumiaki Ishikawa 1 , Chongwu Zhou 3 , Martin Gundersen 1 3
1 Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California, United States, 2 Department of Chemistry, University of Southern California, Los Angeles, California, United States, 3 Department of Electrical Engineering-Electrophysics, University of Southern California, Los Angeles, California, United States, 4 MOSIS, Information Sciences Institute, University of Southern California, Los Angeles, California, United States
Show AbstractIn this work we report uptake of amide-linked single-walled carbon nanotube (CNT)-fluorescein conjugates into SKOV-3 human ovarian cancer cells. The uptake of CNTs is of interest for therapeutic and other biomedical and biological applications. The studies included an investigation of response of endocytosed CNTs to optical excitation. It was found that conjugated CNTs can be observed optically in the intracellular environment, and that in particular the fluorescence emission from cells loaded with amide-linked CNT fluorescein conjugates increases after brief exposure to light. A hypothesis under investigation is that the increased fluorescence arises from free fluorescein released from the CNT fluorescein conjugate by intracellular hydrolysis. These results suggest that light-stimulated intracellular hydrolysis of the amide linkage may be significant in the intracellular biochemistry of this process, and that the variation in local pH in the intracellular environment results in fluorescence variation. The work has demonstrates that CNTs may be delivered to the intracellular environment through endocytosis, and that they have potential applications as bio photonic markers, when properly conjugated, and as indicators of biophysical processes.
10:45 AM - EE15.6
Perfectly Aligned Nanowires on Plastic Substrates for Ultra-Sensitive Flexible Sensors.
Michael McAlpine 1 , James Heath 1
1 Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, United States
Show Abstract Integrating high performance electronics on non-crystalline substrates such as glass and plastic could enable exciting avenues in fundamental research and novel applications. Plastic substrates are especially interesting due to their shatter-proof flexibility and biocompatibility. However, the temperature restrictions imposed by these substrates limit their use to low carrier mobility semiconductors such as amorphous silicon and organic semiconductors. The development of an ambient temperature route for producing and integrating high-mobility semiconductors on flexible substrates could impact a broad spectrum of applications. One area of particular relevance is chemical and biological sensing, which if implemented on biocompatible substrates could provide medical breakthroughs in implantable monitoring systems. In this regard, nanostructures such as nanotubes or nanowires have been shown to be particularly sensitive transducers for electrical sensors because their surface areas are large relative to their volumes, and their diameters are comparable to the sizes of many biological and chemical species. Here, we present an ambient, highly scalable and parallel process for transferring hundreds of pre-aligned silicon nanowires onto flexible plastic to yield arrays of ultra-sensitive sensors. Specifically, a superlattice pattern transfer process is employed to produce a film of perfectly aligned 20-nm nanowires at a regular 30-nm pitch on silicon-on-insulator wafers. Elastomeric stamps are subsequently used to peel the wires from the host wafer and comprehensively transfer them to a flexible plastic substrate. Significantly, this transfer process does not disrupt the pristine nano-morphology of the aligned wires. Standard photolithography techniques are used to electrically address the nanowires, resulting in thin film transistors with device characteristics rivaling state-of-the-art macroelectronics. Furthermore, electrical sensors made from nanowire-on-plastic devices show parts-per-billion detection sensitivity when exposed to common pollutant gases. The excellent device performance of the nanowires coupled with the biocompatibility of the plastic substrate opens up exciting opportunities for portable, wearable, or even implantable biological and chemical sensors.
11:30 AM - **EE15.7
Applications and Properties of Nanowire Meshes
Brian Korgel 1
1 Chemical Engineering, University of Texas at Austin, Austin, Texas, United States
Show AbstractSolution routes can achieve high yields of crystalline high aspect ratio semiconductor nanowires of a wide variety of materials, including Group IV, III-V and II-VI semiconductors. These nanowires have been proposed as the basis for many new technologies, yet none of these have been realized commercially. One of the challenges facing real-world applications of nanowires is the sensitivity of their properties (i.e., electrical and optical) on their surface chemistry. Their extremely large surface area-to-volume ratios provide a unique property that might be utilized in new transistor structures that can yield very high inversion currents or in new sensors that rely on subtle changes in conductivity or dielectric constant in the presence of an analyte; however, effective, robust methods for controlling their surface chemistry must be realized. A library of surface modification chemistry is available that can be applied to the surfaces of the nanowires, yet there has been little detailed study of the influence of surface chemistry on nanowire properties to date. I will briefly discuss the influence of different surface chemical treatments on the electronic properties of Ge nanowires, such as their field effect mobility. Then I will discuss a few possible design configurations and processing strategies that might make it possible to utilize the very high surface area to volume ratios of nanowires effectively in electronic and sensing applications by fabricating device constructions based on nanowire meshes. These nanowire meshes could be utilized for chemical sensing for example. I will present the synthesis, fabrication and properties of such a structure.
12:00 PM - EE15.8
Polarization-sensitive Photodetectors based on Solution-synthesized CdSe and CdTe Quantum Wire Solids.
Amol Singh 1 , Debdeep Jena 1 , Vladimir Protasenko 2 , Masaru Kuno 2 , Huili Xing 1
1 Electrical Engineering, University of Notre Dame, Notre Dame, Indiana, United States, 2 Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States
Show Abstract12:15 PM - EE15.9
Bio-functional Subwavelength Optical Waveguides for Chemical Detection
Donald Sirbuly 1 , Olgica Bakajin 1 , Aleksandr Noy 1
1 Chemistry, Materials, and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California, United States
Show Abstract Compact, reusable biochemical sensors are highly desirable for rapid on-site analytical analysis of gas and liquid mixtures in the field. A key to miniaturizing devices and providing reliable quantitative chemical identification of small sample volumes hinges on the development of novel materials capable of multiple complementary sensing modalities. Here we build a bio-functional optical sensing platform that utilizes the evanescent field of a subwavelength nanowire waveguide to detect single biochemical molecules. The optical cavities are integrated into polymeric flow cells for rapid chemical functionalization, multiplex sensing and reusability. The biocompatibility of the waveguide is assured by assembling fluid lipid membranes tagged with receptor molecules within the evanescent field. With the advantage of carrying out multiple spectroscopy techniques such as absorbance, fluorescence and surface enhanced Raman spectroscopy (SERS) on sub-picoliter probe volumes, these evanescent field sensors offer a unique design for portable all-optical detection systems.This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.
12:30 PM - EE15.10
Fabrication and Characterization of Single TiO2 Nanotube Enhanced Humidity Sensor Device by UV Treatment.
Dongkyu Cha 1 , Bongki Lee 1 , Moon.J Kim 1 , Hyunjung Shin 2 , Jaegab Lee 2 , Jiyoung Kim 1
1 MSE, university of texas at dallas, Richardson, Texas, United States, 2 School of Advanced Engineering , Kookmin University, Seoul Korea (the Republic of)
Show AbstractFriday, April 13New Presentation Time and Paper NumberEE15.11 @ 11:45 am to EE15.10 @ 11:30 amFabrication and Characterization of Single TiO2 Nanotube Enhanced Humidity Sensor Device by UV Treatment.Dongkyu Cha
EE16: : Sensors, Emitters and Structural Materials II
Session Chairs
Friday PM, April 13, 2007
Room 2016 (Moscone West)
2:30 PM - **EE16.1
Carbon Nanotubes and Inorganic Nanowires for Sensors and Nanodevices
Meyya Meyyappan 1
1 Center for Nanotechnology, NASA Ames Research Center, Moffett Field, California, United States
Show AbstractOne dimensional nanostructures such as carbon nanotubes and inorganic nanowires exhibit interesting physical, electrical, and other properties ideal for applications in sensors, nanoelectronics and other nanodevices. Purified single walled carbon nanotubes(SWNTs) have been used as sensor medium in an interdigitated microelectrode structure for developing chemical sensors. The conductivity of the SWNTs changes reproducibly when exposed to various gases and vapors. Results for sensitivity and selectivity for various gases and vapors in mixtures will be presented along with effects of humidity, temperature and radiation effects for use in space applications. Our progress in the fabrication of biosensors using a carbon nanofiber nanoelectrode array and integration with microfluidics will be described. Finally, Vapor-liquid-solid growth of nanowires of nitride, antimonide and phase change materials will be described in the context of optoelectronics and memory applications. The author acknowledges the contributions of Jing Li, Jun Li, Bin Yu, C. J. Ning, S. Vaddiraju, and Prof. M. Sunkara
3:00 PM - EE16.2
Carbon Nanotube Coatings for Pyroelectric Detectors Used for Precise Measurement of Laser Power.
Anne Dillon 1 , Rohit Deshpande 1 , Paul Rice 2 , Kathrine Hurst 2 , John Lehman 2
1 , National Renewable Energy Laboratory, Golden, Colorado, United States, 2 , National Institute of Standards and Technology, Boulder, Colorado, United States
Show Abstract3:15 PM - EE16.3
Graphene Sheet Research and Fracture of SWCNTs.
Rod Ruoff 1 , Dima Dikin 1 , James Hone 2 , Weiqiang Ding 1 , Mingyuan Huang 2
1 Mechanical Engineering, Northwestern University, Evanston, Illinois, United States, 2 Mechanical Engineering, Columbia University, New York, New York, United States
Show AbstractWe present our work on graphene-based materials and then turn to a discussion of the fracture mechanics of single-walled carbon nanotubes identified in terms of diameter and chirality (thus, of known n and m indices).
3:30 PM - EE16.4
Hydrogen Storage in Carbon Nanotubes Through the Formation of C-H Bonds
Anton Nikitin 1 , XiaoLin Li 3 , Zhiyong Zhang 2 , David Mann 3 , Hirohito Ogasawara 1 , Ali Pour Merhabi 4 , Hongjie Dai 3 , Anders Nilsson 1 4
1 , Stanford Synchrotron Radiation Laboratory, Menlo Park, California, United States, 3 , Department of of Chemistry, Stanford University, Stanford, California, United States, 2 , Department of Mechanical Engineering, Stanford University, Stanford, California, United States, 4 , FYSIKUM, Stockholm University, Stockholm Sweden
Show AbstractTo figure out technologically viable way to use carbon based materials for on board hydrogen storage we studied the possibility to use hydrogen chemisorption in the single-walled carbon nanotubes (SWCN). Using X-ray photoelectron spectroscopy as a probing tool and in situ atomic hydrogen treatment we found that depending on the nanotube diameter different hydrogenation degrees of this material can be reached. We demonstrated that for particular types of SWCN H-SWCN complexes with almost 100 % hydrogen coverage of nanotube surface exist and are stable at room temperature. This means that carbon nanotube material can have hydrogen storage capacity more than 7 wt % through chemisorption mechanism and potentially can fulfill DOE requirements for the hydrogen storage medium. The influence of bundling on the hydrogenation process and the insulator character of highly hydrogenated nanotubes are also shown.
3:45 PM - EE16.5
Novel Nanowire-micropillar Functionalized Hierarchical Surfaces for Photo-controlled Movement of Fluids.
Dongqing Yang 1 , P. Aella 1 , Antonio Garcia 2 , Devens Gust 3 , Mark Hayes 3 , S. Picraux 1 4
1 School of Materials, Arizona State University, Tempe, Arizona, United States, 2 Harrington Department of Bioengineering, Arizona State University, Tempe, Arizona, United States, 3 Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona, United States, 4 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show Abstract