David B. Mitzi IBM T. J. Watson Research Center
David Ginley National Renewable Energy Laboratory
Bernd Smarsly Justus Liebig University Giessen
Dmitri V. Talapin The University of Chicago
F1: Nano-Related Deposition
Tuesday PM, December 02, 2008
Room 208 (Hynes)
9:30 AM - **F1.1
Self-organization and Chemical Doping in Solution Processed Semiconductor Nanocrystal Superlattices.
Christopher Murray 1 Show Abstract
1 Chemistry and Materials Science & Eng, University of Pennsylvania, Philadelphia, Pennsylvania, United States
10:00 AM - F1.2
Binary Superlattices of PbSe and CdSe Nanocrystals.
Daniel Vanmaekelbergh 1 , Karin Overgaag 1 , Bart de Nijs 1 , Wiel Evers 1 , Rolf Koole 1 , Mark Boneschanscher 1 Show Abstract
1 Debye Institute for NanoMaterials Science, University of Utrecht, Utrecht Netherlands
The formation of binary superlattices via colloidal crystallization is the most promising method to realize nanostructured solids in which different materials are in near contact and ordered in a well-defined 3-D geometry. Despite the obvious importance for novel applications in opto-electronic materials, studies of nanocrystal superlattices consisting of two types of semiconductor quantum dots have been quite limited (1-3). In this presentation we report on the self-organization of PbSe and CdSe nanocrystals into binary superlattices upon evaporation of the solvent from a mixed suspension at elevated temperatures and reduced pressure (3). We show that, besides the choice of the solvent, the size-and concentration ratio of both types of nanocrystals are the relevant parameters determining the composition and structure of the superlattice. We demonstrate AB, AB2, AB5 and AB13 structures (A=PbSe, B= CdSe) obtained by varying the diameter ratio PbSe/CdSe between 0.5 and 0.8. We show that binary superlattices can have an intricate structure that is best resolved by 3-D TEM (tomography). The results are discussed on the basis of newly developed simulation models based on hard-sphere building blocks. The electronic properties of a number of PbSe/CdSe NC superlattices are currently under study. 1) J. J. Urban et al., Nature Mat. 6, 115 (2007)2) Z. Y. Chen et al. J. Am. Chem. Soc. 129, 15702 (2007)3) K. Overgaag et al., J. Am. Chem. Soc. 130, 7833 (2008)
10:15 AM - F1.3
Thin films of Side-functionalized Poly(3-hexylthiophene) and Thymine-capped CdSe Nanocrystals Obtained by Hydrogen Bond Assisted Layer-by-layer Assembly.
Julia De Girolamo 1 , Adam Pron 1 , Peter Reiss 1 Show Abstract
1 INAC/SPrAM, CEA Grenoble, Grenoble France
Hybrid materials composed of conjugated polymers and semiconductor nanocrystals are promising systems for the fabrication of low cost, large area photovoltaic devices based on the so-called bulk-heterojunction concept. However, in simple blends of both components, generally undesired phase segregation on a submicron level occurs. We present a new approach to overcome this problem and to achieve morphology control of hybrid material thin films. It is based on the molecular recognition process via hydrogen bonding between complementary chemical groups in the side chain of the polymer and on the nanocrystal’s surface.A new copolymer was synthesized, namely poly(3-hexylthiophene) bearing oxydiaminopyrimidine side groups, which are capable of forming triple hydrogen bonds with mercaptohexylthymine-capped CdSe nanocrystals. Due to their different solubility parameters, the functionalized components can be directly deposited on various substrates (glass, ITO, silicon oxide) using the layer-by-layer method. This technique, based on the alternated dipping of the substrate into the polymer solution and into the NCs’ dispersion, allowed us to control the composition and thickness (range: 30-150 nm) of the hybrid films on a molecular level. In addition, the materials’ consumption is significantly reduced in the dip-coating process with respect to the deposition via spin-coating, usually applied for the processing of hybrid materials.Complementary SEM and SAXS investigations of the deposited layers indicate that the polymer and the nanocrystal phases form a quasi-interpenetrating network, which is favourable for their application in thin film solar cells relying on the bulk heterojunction concept. First device tests clearly show the photovoltaic effect with conversion efficiencies in the typical range (0.1% for an active surface of 28 mm2 under AM 1.5 conditions using 100 mW/cm2 simulated white light) observed for blends of 5 nm spherical CdSe NCs with poly(hexylthiophene) or MEH-PPV. Future device improvement is expected through the optimization of the number of deposited bilayers, NCs’ composition, shape and surface chemistry, to list the principal parameters.
10:30 AM - F1.4
Organizing Nanoparticles using Self Assembled Peptide Nanostructures.
Nikhil Sharma 1 2 , Matthew Lamm 1 2 , Darrin Pochan 1 2 Show Abstract
1 Materials Science & Engineering, University of Delaware, Newark, Delaware, United States, 2 , Delaware Biotechnology Institute, Newark, Delaware, United States
The “bottom-up” methodology consists of designing recognition into molecules that then self-assemble into the desired nano-architecture in the appropriate microenvironment. Peptides undergo self-assembly in solution to form hierarchal nanostructures. Herein, we demonstrate the use of a peptidic template for the construction of parallel, linear arrays of inorganic nanoparticles. A 20 amino acid peptide, consisting of alternating hydrophilic (lysine) and hydrophobic (valine) residues flanking a central diproline turn sequence (VKVKVKVKVPPTKVKVKVKV-NH2) was employed as a nano-scale template for the organization of 2nm gold particles. This peptide self assembles into laminated fibrillar morphology in solution and has a periodic nanostructure consisting of alternating hydrophobic and hydrophilic layers with a lateral periodicity of 2.5 nm. Negatively charged gold nanoparticles are templated into the positively charged lysine layer through electrostatic interaction and are aligned within the template that itself swells to a periodic spacing of 4.0 nm in order to accommodate the particles. These 1D nanoparticle arrays have potential applications in fields like nano-electronics, and we are currently attempting to create arrays of quantum dots and hetero-structures of metal and semiconductor particles.
10:45 AM - F1.5
Assembly and Conductivity of Nanocrystal Solids.
Dmitri Talapin 1 2 , Maksym Kovalenko 1 , Elena Shevchenko 2 , Jong-Soo Lee 1 Show Abstract
1 , The University of Chicago, Chicago, Illinois, United States, 2 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, United States
11:30 AM - **F1.6
Structure and Kinetics of Nanocyrstal Self-assembly Probed by Small Angle X-ray Scattering Techniques.
Xiao-Min Lin 1 Show Abstract
1 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, United States
12:00 PM - F1.7
Assembly, Roughness Control, and Arbitrary Chemical-Physical Functionalization of Nanoparticle Thin Films for Optical Applications.
Zekeriyya Gemici 1 , Hiroomi Shimomura 2 , Robert Cohen 1 , Michael Rubner 2 Show Abstract
1 Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Nanoparticles are indispensable ingredients of solution-based optical, dielectric, and catalytic thin films. While solution-based methods are promising low-cost alternatives to vacuum methods, they can have significant limitations. Coating uniformity, thickness control, roughness control, mechanical durability, and incorporation of a diverse set of functional organic molecules into nanoparticle thin films are major challenges.We have used the electrostatic layer-by-layer (LbL) assembly technique to make uniform, conformal multi-stack nanoparticle thin films for optical applications with precise thickness control over each stack. Two particularly sought-after optical applications are broadband antireflection (AR) and structural color. The effects of inter-stack and surface roughness on optical properties of these constructs (e.g., haze and spectral response) have been studied quantitatively using a combination of Fourier-transform methods and atomic force microscopy (AFM) measurements. Deconvoluting root-mean-square (RMS) roughness into its large-, intermediate-, and small-scale components enables enhanced optical simulations. A 4-stack broadband AR coating (<0.5% average reflectance in the visible range, and 0.2% haze) composed of alternating high-index (n~2.1) and low-index (n~1.3) stacks has been made on glass substrate. Films calcinated at 550°C endure a one-hour-long cloth cleaning test under 100 kPa normal stress.Beyond the direct assembly of multi-stack nanoparticle thin films, it would be highly desirable to identify post-assembly modification methods that supplement thickness and roughness control with chemical functionalization. Hydrophilic, hydrophobic, reactive, or inert chemical vapors capillary-condense in the vicinity of contact points between nanoparticles with equal facility. This phenomenon can be used advantageously to functionalize nanoparticle assemblies. The volume fraction of the condensate is particle size-dependent, which allows targeted functionalization in a multi-stack LbL assembly. 2-stack films composed of 8nm and 50nm SiO2 particles on the bottom and top stacks, respectively, were functionalized with oligomers (e.g., PDMS) or UV-sensitive monomers (e.g., tri(ethyleneglycol) dimethacrylate (TEGDMA)). The condensate volume fraction in the bottom stack was significantly higher than that in the top stack, and excellent broadband AR functionality (<0.6% average reflectance in the visible range) resulted from a mere 160nm-thick film. UV-crosslinking ability was demonstrated for TEGDMA-functionalized films. The PDMS-functionalized film was also assembled on epoxy microlenses, and showed no optical or mechanical failure upon repeated rapid (30s) heating-cooling cycles between 25°C and 260°C. Finally, we show that capillary condensation can be used to enhance mechanical durabilities of otherwise delicate nanoparticle assemblies, as well as to prevent their physical-chemical vulnerability to moisture.
12:15 PM - F1.8
Nanopatterning of Narrow-Gap Quantum Dots via “Soft” Electron Beam Lithography (soft-eBL).
Bin Liu 1 , Aiming Yan 1 , Tao Sun 1 , Indika Arachchige 2 , Mercouri Kanatzidis 2 , Vinayak Dravid 1 3 Show Abstract
1 Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States, 2 Department of Chemistry, Northwestern University, Evanston, Illinois, United States, 3 International Institute of Nanotechnology, Northwestern University, Evanston, Illinois, United States
Significant progress in the synthesis of narrow-gap quantum dots, such as PbTe nanocrystals, has triggered recognition of their potential in photovoltaic, thermovoltaic, and thermoelectric applications. Some of the recent advances in enhancing the thermoelectric figure of merit are associated with these materials, due to the strong quantum-confinement effect as well as large phonon scattering. It is essential to develop techniques to fabricate nanostructures containing quantum dots to obtain not only the desired internal microstructures and grain boundary properties, but also to simultaneously maintain the nanoscale particle size. Furthermore for building devices, the site-specificity of the technique and its compatibility with traditional microfabrication procedures are also required. In this study, a versatile nanopatterning approach, soft-eBL, is being employed to prepare various nanostructures. By collectively combining electron beam lithography and deposition of solution precursors of narrow-gap quantum dots, nano-rings/dots/lines of PbTe or/and SnTe are fabricated. By tuning preparation conditions, the nanocrystals are directed to exhibit either short range or long range packing order, which has been confirmed by high-resolution scanning electron microscopy (HRSEM) and scanning transmission electron microscopy (STEM). Quantum-dot nanolines, different from thin-film superlattices, introduce the confinement in one more dimension, which have been confirmed by theoretical study to show higher figure of merit. Chemical treatment with hydrazine and mild heating are performed to increase the electrical conductivity while maintaining high phonon scattering, and thus to increase the thermoelectric figure of merit. Moreover, the nanocrystals with n- or p-typesemiconducting property are also being built into field-effect transistors, which serve as good alternatives to traditional semiconductor circuits. The presentation will cover aspects of soft-eBL nanopatterning and measurements of colloidal assembly of thermoelectric nanostructures.
12:30 PM - F1.9
Broad-Band, Low-Threshold Amplified Spontaneous Emission from Giant Nanocrystal Quantum Dots.
Florencio Garcia-Santamaria 1 , Yongfen Chen 1 , Richard Schaller 1 , Jennifer Hollingsworth 1 , Victor Klimov 1 Show Abstract
1 Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Nanocrystal quantum dots (NQDs) are nanosized crystalline semiconductor particles that show near-unity photoluminescence quantum yields and size-dependent emission colors tunable through the quantum-confinement effect. Because of these properties, nanocrystals are attractive materials for various light-emitting applications including optical amplification and lasing. Due to the almost exact balance between absorption and stimulated emission in nanoparticles excited with single electron-hole pairs (excitons), optical gain can only occur when nanocrystals contain at least two excitons. A complication associated with this multiexcitonic nature of light amplification is fast, picosecond optical-gain decay induced by nonradiative Auger recombination, in which one exciton recombines by transferring the energy to the other. A few years ago, it was demonstrated that close-packed films of NQDs can still show both optical gain and amplified spontaneous emission (ASE) when excited with short and intense laser pulses . However, the ASE thresholds are quite high (several mJ/cm2), which seriously hinders lasing applications of NQDs. Here, we present new results from our studies of dense films made of a new type of nanocrystals dubbed “giant” quantum dots (g-NQDs) . These NQDs comprise an emitting core particle of CdSe overcoated with a very thick shell (up to 20 monolayers) of wider-gap CdS. For this new type of NQD, we observe that the ASE threshold drops down to just a few μJ/cm2, which is almost three orders of magnitude lower than that previously reported for CdSe NQDs. We explain this result by a significant increase in the absorption cross-section of g-NQDs compared to traditional nanocrystals and lengthening of biexciton lifetimes. We also observe other unusual optical-gain behaviors for these structures such as multi-band ASE spectra, in which the band-edge emission co-exist with stimulated emission features due to transitions involving excited electronic states. The overall spectral range of optical amplification extends over more than 500 meV; such broad-band ASE has never been previously observed for other types of optical gain media. These results demonstrate that g-NQDs are very promising materials for applications in practical lasing technologies. V. I. Klimov, A. A. Mikhailovsky, Su Xu, A. Malko, J. A. Hollingsworth, C. A. Leatherdale, H.-J. Eisler, M. G. Bawendi, Optical Gain and Stimulated Emission in Nanocrystal Quantum Dots, Science 290, 314 (2000). Y. Chen, J. Vela, H. Htoon, J. L. Casson, D. J. Werder, D. A. Bussian, V. I. Klimov, J. A. Hollingsworth. “Giant” Multishell CdSe Nanocrystal Quantum Dots with Suppressed Blinking, J. Am. Chem. Soc. 130, 5026 (2008)
12:45 PM - F1.10
Electroluminescence from Core/Doped-Shell Nanoparticles using Transparent Metal Oxides.
Vanessa Wood 1 , Jonathan Halpert 2 , Matthew Panzer 1 , Moungi Bawendi 2 , Vladimir Bulovic 1 Show Abstract
1 Department of Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts, United States, 2 Department of Chemistry, MIT, Cambridge, Massachusetts, United States
F2: Solution Processed Electronic/Optical Films and Devices
Tuesday PM, December 02, 2008
Room 208 (Hynes)
2:30 PM - **F2.1
Nanocrystal-Based Thin Film Optoelectronic Devices: Deposition and Characteristics.
Moungi Bawendi 1 Show Abstract
1 Department of Chemistry, MIT, Cambridge, Massachusetts, United States
3:00 PM - F2.2
Patterned Deposition of Solution-Processed Colloidal Nanocrystal Quantum Dots for LEDs Aplications.
Jian Xu 1 , Ting Zhu 1 , Fan Zhang 1 , Jerzy Ruzyllo 2 , Yongqiang Wang 3 Show Abstract
1 Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania, United States, 2 Electrical Engineering, Penn State University, University Park, Pennsylvania, United States, 3 , Ocean NanoTech LLC, Fayetteville, Arkansas, United States
The emergence of colloidal quantum dot-based light emitting diodes (QD-LEDs) offers a great prospect for developing low-cost, efficient, bright, color-saturated, large-area color displays compatible with flexible substrates. An imminent hurdle along the roadmap to QD-LED-based displays is, however, the lack of an appropriate technology to efficiently deposit and pattern QD-layers with precise controls over thickness, composition, surface morphology, and resolution needed to fabricate RGB-pixel arrays of bright QD-LEDs over large surface areas for passive/active matrix displays. Compared to most solution-processed organic LEDs, the efficiency and brightness of QD-LEDs are highly dependent on the thickness of the emissive QD-layer in the device active region. To date, almost all the record-performances of QD-LEDs have been achieved with devices containing QDs of 1-5 monolayer (ML)-thickness. Thicker QD-active regions result in an increase of the operating voltage and decrease of the carrier-injection efficiency due to the slow dot-dot transport. In this conference we will introduce a process of mist-deposition which allows for the simultaneous assembly and patterning of QDs in QD-LED fabrication with precise controls over thickness. The technology of mist deposition was originally developed for the liquid-source chemical deposition of ultra-fine films of ferroelectrics, high-k dielectrics for MOS gates and other applications in the microelectronics industry. It was adapted in the present work to deliver emissive QDs for the formation of ultrathin active layers in QD-LEDs. During the deposition submicron mists of QD solutions are softly and uniformly transported onto the substrate surface, where they subsequently coalesce at a controlled rate, allowing for a higher degree of thickness- and morphology-control as well as lower waste as compared to spin coating. Microscopic characterization of mist-deposited QD-films has indicated that tight controls over the thickness and surface morphology of QD-layers can be achieved by tailoring the process variables. A QD-LED containing the mist-deposited emissive QD-layer was demonstrated with defect-free and uniform brightness. Furthermore, the technique of successive mist-deposition of multi-color QDs through a set of registered shallow masks was employed to create and investigate a 6×6 matrix of alternating pixels composed of 5nm-diameter CdSe(ZnS) QDs (green) and 8nm-diameter CdSe(ZnS) QDs (red) on a single substrate, suggesting the full capacity of mist-deposition technology in the future development of colorful QD-LED displays. It is expected that superior QD-LED performance can be achieved by optimizing the multiple parameters in the mist-deposition process. The demonstrated approach provides a solid platform for the next-stage development of multicolor QD-LED matrices by selectively mist-depositing multispectral QDs with shadow masks.
3:15 PM - F2.3
Ambipolar Behavior in Ion Gel Gated PbSe Nanocrystal Thin Film Transistors.
Moon Sung Kang 1 , Jiyoul Lee 1 , David Norris 1 , C. Daniel Frisbie 1 Show Abstract
1 Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, United States
We present a new type of field-effect transistor (FET) based on films of PbSe nanocrystal in combination with ion gels as the dielectric material. Prior to applying ion gel, PbSe nanocrystal films were treated with hydrazine and stored under vacuum. Gating the film with a conventional SiO2 dielectric, p-channel FETs were obtained with hole mobilities of 0.08 cm2/Vsec and current modulation of < 102 with applied gate voltage of -100 V to 100 V . The same nanocrystal film was then gated with ion gel dielectric, which has large specific capacitance (~ 30 μF/cm2). Ambipolar behavior was observed with improved device performance. In particular, the ambipolar transistor yielded electron and hole mobilities up to 1.9 and 0.2 cm2/Vsec, respectively and current modulations of 102 to 103 with applied gate voltage of -2 V to 2 V.
3:30 PM - F2.4
Nanoscale Zinc Oxide as Semiconductor Material in a Printed Field Effect Transistor Device.
Joerg Schneider 1 , Rudolf Hoffmann 1 , Andreas Klyszcz 2 Show Abstract
1 Chemistry, TU Darmstadt, Darmstadt Germany, 2 , Merck, KGaA, Darmstadt Germany
It is a challenge to develop flat printable electronics based solely on inorganic materials as an active semiconductor. This could be the basis for flexible displays or electronic paper when the active material is processable from solution, shows very good adherence to flexible substrates and excellent physical performance. To meet these challenges any material considered requires a tuned set of functional properties. In general inorganic semiconductors are in advantage over organic materials as far as their physical performance is concerned. However, often processing and adherence to substrates is a problem with inorganic semiconductors. ZnO is available in various morphologies as transparent oxide, it is non toxic, inexpensive and is well known for its promising physical semiconductor properties. Despite a couple of recent reports on the deposition of zinc oxide thin layers in FET devices, processing from solution and conversion into the active FET channel electrode under fairly mild conditions is a great challenge. Chemical bath deposition techniques and sol-gel processes were mainly investigated in this regard. However, both techniques typically require either high processing temperatures (above 300°C) or long reaction times and are thus inappropriate for printing applications on flexible polymer based substrates under state of the art printing conditions. Processing temperatures well below 200° C are the goal for the formation of semiconducting inorganic thin films onto such substrates. We will report on synthesis of a molecular precursor, its use in the formation of naocrystalline ZnO and its conversion into self adhering films which can be deposited on plastics as well as more conventional substrates. Moreover the electrical performance of nanocrystalline ZnO derived therefrom is reported.
3:45 PM - F2.5
High Performance Polymer/ceramic Nanocomposites Based on Surface-modified Metal Oxide Nanoparticles using Functional Phosphonic Acids for Electronic Applications.
Philseok Kim 1 , Simon Jones 1 , Peter Hotchkiss 1 , Xiao-hong Zhang 2 , Natalie Doss 1 , John Tillotson 1 , Benoit Domercq 2 , Joshua Haddock 2 , Jiangyu Li 3 , Bernard Kippelen 2 , Yingying Lu 4 , Qing Wang 4 , Seth Marder 1 , Joseph Perry 1 Show Abstract
1 School of Chemistry and Biochemistry, Georgia Inst. of Technology, Atlanta, Georgia, United States, 2 School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States, 3 Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States, 4 Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania, United States
Polymer/ceramic nanocomposites benefit by combining high permittivities (k) of metal oxide nanoparticles with solution-processibility and high dielectric strength of polymeric hosts. Simple mixing of nanoparticles and polymer generally results in poor quality materials due mainly to the agglomeration of nanoparticles and poor miscibility of nanoparticles in host materials. We have shown that surface modification of metal oxide nanoparticles with phosphonic acid-based ligands affords robust surface modification and improves the processiblity and the quality of nanocomposites. We report on the use of phosphonic-acid modified barium titanate (BaTiO3) nanoparticles in dielectric nanocomposites and their applications to high-energy-density capacitors and solution-processible high permittivity gate insulators in organic field-effect transistors (OFETs). Surface modification of BaTiO3 nanoparticles allowed high quality nanocomposite thin films in ferroelectric polymer hosts such as poly(vinylidene-co-hexafluoropropylene) and poly(vinylidenefluoride-co-trifluoroethylene-co-chlorotrifluoroethylene) with large volume fractions (up to 50 vol. %), which are potentially useful materials for electrical energy storage. Similarly, the use of phosphonic acid-modified BaTiO3 nanoparticles in cross-linked poly(4-vinylphenol) allowed to form solution-processible high permittivity nanocomposite gate insulators for organic field-effect transistors. High quality nanocomposite thin films at large nanoparticle volume fractions (up to 37 vol. %) with a large capacitance density (~50 nF/cm^2) and a low leakage current (10^-8 A/cm^2) were obtained. Pentacene-based p-type OFETs using these nanocomposites showed a large on/off current ratio (Ion/off 10^4 - 10^6) due to the high capacitance density and small leakage current of the gate insulator. We will also present the results from a recent experimental and theoretical study where the BaTiO3 nanoparticle volume fraction was systematically varied in a high permittivity (k = 11) host to find the optimum permittivity and dielectric strength providing a guideline to optimize the volume fractions for achieving maximum energy storage density.
4:30 PM - **F2.6
Chemically Derived Nanostructures for Emerging Challenges in Semiconductor Electronics.
Xiangfeng Duan 1 Show Abstract
1 Chemistry and Biochemistry, UCLA, Los Angeles, California, United States
5:00 PM - F2.7
Rapid Electrical Sintering of Nanoparticle Stuctures.
Mark Allen 1 , Mikko Aronniemi 1 , Ari Alastalo 1 , Tomi Mattila 1 , Kimmo Ojanpera 1 , Mika Suhonen 1 , Heikki Seppa 1 Show Abstract
1 VTT Sensors and Wireless Devices, VTT, Espoo Finland
We present a method to electrically sinter nanoparticle structures [1,2]. For an inkjetted silver nanoparticle conductor, a conductance increase of more than five orders of magnitude is demonstrated to occur in less than a millisecond such that most of the conductance change (four orders of magnitude) takes only a few microseconds.The demonstrated method is an alternative to, for example, conventional thermal (oven) sintering, laser sintering , photonic sintering  and microwave sintering .A central prerequisite for the rapidness of the curing process is the voltage boundary condition. Namely, the resistivity of the printed structure being a decreasing function of local temperature results in increase of power dissipation and thus causes a strong positive feedback. The obtained final conductivities are within a factor of two from the bulk silver conductivity, as calculated for the external geometric dimensions of the structure which overestimates the particulate structure volume. The experiments have been performed at ambient temperature (without any convective or radiative heating).The central benefits of the method include (i) reduced substrate heating as illustrated by fabricating high-quality conductors on a paper substrate that does not tolerate the oven sintering temperature of the ink, (ii) easy control of the final conductivity level with external bias resistors, and (iii) suitability of the method for area-specific processing (direct writing).To gain insight into the electrical sintering process, we have performed modelling which takes both macroscopic material properties as well as electron tunnelling processes into account. The experimental results include IR (λ ~ 10um) video microscopy. In addition to metallic conductors, the method is potentially applicable to other inorganic conductors such as indium-tin-oxide (ITO) and semiconducting materials. More generally, the method offers a versatile tool in nanotechnology for electrical functionalization of the nanoparticle structures. Mark L Allen, Mikko Aronniemi, Tomi Mattila, Ari Alastalo, Kimmo Ojanperä, Mika Suhonen and Heikki Seppä, Nanotechnology 19 175201 (2008). M. Allen and H. Seppä, Patent Application WO2008009779A1. N.R. Bieri, J. Chung , S.E. Haferl, D. Poulikakos D andC.P. Grigoropoulos, Appl. Phys. Lett. 82 3529 (2003).  K. A. Schroder, S. C. McCool and W. R. Furlan, NSTI Nanotech 2006. www.novacentrix.com.  J. Perelaer, B.-J. deGans and U.S. Schubert , Adv. Mater. 18 2101 (2006).
5:15 PM - F2.8
Thermal and Photo-Induced Phase Transformations ofSilver(I)-2-[2-(2-methoxyethoxy)-ethoxy]acetat.
Alexander Jakob 1 , Stephan Jahn 2 , Afshin Abbasi 3 , Thomas Blaudeck 2 , Cameliu Himcinschi 4 , Marion Friedrich 4 , Heinrich Lang 1 , Reinhard Baumann 2 , Michael Schreiber 3 , Dietrich R. T. Zahn 4 Show Abstract
1 Inorganic Chemistry, TU Chemnitz, Chemnitz Germany, 2 Print and Media Technology, TU Chemnitz, Chemnitz Germany, 3 Theory of Disordered Systems, TU Chemnitz, Chemnitz Germany, 4 Semiconductor Physics, TU Chemnitz, Chemnitz Germany
Silver(I)-complexes and derivatives can serve as precursors for the metallization of various materials used in contemporary microelectonics , as the metallization process mainly comprises a spin-on deposition of the dissolved precursor on the substrate followed by a subsequent thermal treatment. However, for most flexible substrates used in organic and large-area electronics, the metallization is a severe challenge as the respective approaches have to cope with the limited thermal stability of the materials in use. We report on silver(I)-2-[2-(2-methoxyethoxy)-ethoxy]acetat (usually known for thermographic and photothermic imaging) as a suitable precursor molecule for a photo-induced metallization of substrates with limited stability. Comparative monitoring of thermal and photo-induced transformation processes by conductance measurements, Raman and Fourier transform infrared (FTIR) spectroscopy along with density functional theory (DFT) calculations indicates that the formation of metallic layers from the wet-deposited films comprises at least two solid-state phase transformations. Our experiments complement the studies by Olson et al. which discuss the subsequent formation of metallic silver nanoparticles and micro-islands during the thermally induced reduction of silver carboxylates .The knowledge on the physical and chemical details of the transformation process may pave the way for a replacement of the thermal treatment by alternative techniques suitable for substrates with low thermal stability such as poly(ethylene terephthalate) (PET).
5:30 PM - F2.9
Solution Processed Silver Sulfide Filament Memories.
Shong Yin 1 , Vivek Subramanian 1 Show Abstract
1 Electrical Engineering, UC Berkeley, Berkeley, California, United States
Ionic resistive switches are emerging as a potential successor for flash in non-volatile memory applications. In ionic switches, metal cations migrate through a solid electrolyte forming filaments on an inert cathode that results in an abrupt increase in conductivity. This process is reversible, and the switches may be reverted to a low-conductive state. These switches have low transition voltages and fast read speed. The low switching energy potentially makes them more scalable than many other resistive memories. Silver Sulfide Resistive switches have been fabricated by sulfidizing evaporated silver films in Sulfur solutions. XPS is used to quantify stoichiometry of resultant films. SEM and AFM indicate that surface roughness increases with sulfidation time as the bulk silver film is consumed in forming the silver sulfide. XRD has confirmed presence of the acanthite phase of Silver Sulfide in the films. The entire process is performed at temperatures below 200C, so the devices are potentially stackable over conventional CMOS substrates in a BEOL process, and are applicable to printable electronics on plastic substrates. Initial characteristics measured on these cells are very promising, exhibiting low energy switching and good programming margins. Write/Erase voltages for cells were 400mV and -200mV respectively. Ron/Roff ratios range from 10 to 10,000 depending on process conditions. Impact of bath concentration, bath temperature and post-annealing on the silver sulfide film structure and ionic conducting properties are studied.
5:45 PM - F2.10
Microfabrication using UV Photo-patternable Semiconductor Nanocrystals.
Won Jin Kim 1 , Sung Jin Kim 1 2 , Marek Samoc 1 , Alexander Cartwright 1 2 , Paras Prasad 1 2 3 Show Abstract
1 Institute for Lasers, Photonics and Biophotonics, University at Buffalo, State University of New York, Buffalo, New York, United States, 2 Electrical Engineering, University at Buffalo, State University of New York, Buffalo, New York, United States, 3 Chemistry, University at Buffalo, State University of New York, Buffalo, New York, United States
F3: Poster Session: Nano and Electronic Devices
Wednesday AM, December 03, 2008
Exhibition Hall D (Hynes)
9:00 PM - F3.1
Monolayer Film of Gold Nanoparticles on a 3 inch or Larger Silicon Wafer.
Matthew Martin 1 , Sang-Kee Eah 1 Show Abstract
1 Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York, United States
We report a very easy, simple, and cheap fabrication method for depositing a monolayer film of gold nanoparticles on any substrate without any size limitation. We present a hexagonal close-packed monolayer of 7 nm gold nanoparticles on a 3 inch silicon wafer. For this purpose we have been developing a new method for chemical synthesis of 3-7 nm gold nanoparticles coated with organic molecules with a special property of floating at the air-toluene interface of a toluene droplet. There they form a hexagonal close-packed monolayer, which can be deposited to any substrate after the toluene molecules' evaporation. There is no size limitation, since a toluene droplet can be as large as 3 inches or larger covering the whole surface of a substrate like a silicon wafer.We chemically synthesize gold nanoparticles in water by mixing an aqueous solution of H+, AuCl4-, and Cl- with an aqueous solution of OH-, BH4-, and Na+. By mixing the two solutions as uniformly and quickly as possible, we can make nearly monodisperse gold particles in water in the diameter range of 3-7 nm. These gold nanoparticles are phase transferred to hexane with 1-dodecanethiol (DDT) molecules simply by vigorous shaking for 1 minute. During the shaking, DDT molecules coat gold nanoparticles and extract them from the water phase to the hexane phase. We found out that these gold nanoparticles coated with hydrophobic organic molecules are negatively charged in a non-polar solvent, hexane. They are stable in hexane but unstable in toluene. If we mix a droplet of hexane containing these gold nanoparticles with a toluene droplet, the gold nanoparticles float at the air-toluene interface as the hexane molecules evaporate 4 times faster than the toluene molecules.In this two-dimensional (2D) self-assembly the purity of the gold nanoparticles solution is very important, because all the non-volatile impurities remain on the substrate after the evaporation of the volatile solvent molecules. Bigioni et al.  reported a similar 2D self-assembly method for gold nanoparticles, where they emphasize the importance of the excess DDT molecules and propose the mechanism of their 2D self-assembly as the organic surfactant molecules cover the interface and ‘attract’ gold nanoparticles. Therefore the monolayer film of gold nanoparticles contains a lot of DDT molecules beneath or above the gold nanoparticles monolayer. In our case the gold nanoparticles solution in hexane is very clean with the only impurity of excess DDT molecules, which can be precisely controlled during the chemical synthesis. All the reaction byproducts remain in the water phase. We present results related to the effects of excess DDT molecules on the quality of the gold nanoparticles monolayer, such as the presence of regions without gold nanoparticles. T.P. Bigioni, X.-M. Lin, T.T. Nguyen, E.I. Corwin, T.A. Witten, & H.M. Jaeger, Nature Mater. 5, 265–270 (2006).
9:00 PM - F3.10
Optimization of Inkjet Printed CdSe/ZnS Quantum Dot Packing via Bifunctional Self-Assembled Monolayer.
Hanna Haverinen 1 2 , Andrew Wang 3 , Risto Myllyla 2 , Ghassan Jabbour 1 2 4 Show Abstract
1 , Flexible Display Center at Arizona State University, Tempe, Arizona, United States, 2 , University of Oulu, Oulu Finland, 3 , Ocean Nanotech, Fayetteville, Arkansas, United States, 4 , Advanced Photovoltaics Center, Tempe, Arizona, United States
9:00 PM - F3.11
An Evaporative Co-assembly Method for Highly-Ordered Inverse Opal Films.
Benjamin Hatton 1 , Lidiya Mishchenko 1 , Joanna Aizenberg 1 Show Abstract
1 School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States
9:00 PM - F3.13
Stable Binary Complementary White Light Emitting Diodes based on Quantum Dot/Polymer Bilayer Structures.
Zhanao Tan 1 , Brittany Hedrick 1 , Fan Zhang 1 , Ting Zhu 1 , Shuai Gao 1 , Jian Xu 1 , Ron Henderson 2 Show Abstract
1 Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania, United States, 2 Department of Physics, Middle Tennessee State University, Murfreesboro, Tennessee, United States
A binary complementary white light-emitting-diode (LED) was designed and fabricated by employing a colloidal quantum-dot (QD)/polymer-bilayer configuration in the device active region. Stable white electroluminescence was observed from the fabricated device, arising from the additive mixture of the emission from the yellow-emitting CdSe/ZnS core-shell QDs and blue-emitting poly(N,N’-bis (4-butylphenyl)- N,N’-bis(phenyl)benzidine) (Poly-TPD) molecules. The white chromaticity of the LED output can be tailored by varying the respective thicknesses of the constituent emissive layers; whereas the emission color exhibits little dependence on the applied bias over a wide voltage rang. The maximum luminance of the device reaches 2600 cd/m2 under a bias of 9.4 V.
9:00 PM - F3.14
Ultraviolet Ozone Sintering of Pd Nanoparticles.
Liwei Huang 1 2 , Yayong Liu 1 , Howard Wang 1 2 , Sushil Satija 2 , Bulent Akgun 2 Show Abstract
1 Mechanical Engineering, Binghamton University, Binghamton, New York, United States, 2 NCNR, National Institute of Standards and Technology, Gaithersburg, Maryland, United States
9:00 PM - F3.15
Fabrication of PLZT Film-on-Foil Dielectric Sheets for Embedded Passives.
Beihai Ma 1 , Manoj Narayanan 1 , U. (Balu) Balachandran 1 Show Abstract
1 Energy Systems Division, Argonne National Laboratory, Argonne, Illinois, United States
Ferroelectric film-on-foil capacitors hold special promise to replace discrete passive components in the development of electronic devices that require greater performance and smaller size. High permittivity ferroelectric thin films were deposited on base metal foils by chemical solution deposition to form film-on-foil capacitor sheets. These capacitors can be embedded into printed circuit boards (PCBs). However, the formation of a parasitic low permittivity interfacial oxide layer during thermal processing of the ferroelectric significantly reduces the capacitance density. Two approaches were taken to overcome this challenge. In the first, a conductive oxide buffer layer acting as a bottom electrode is inserted between the ferroelectric and the metal foil to obviate the deleterious interfacial oxide. In the second, the high temperature processing is done under low oxygen partial pressures such that no interfacial oxide is formed. We have grown high quality ferroelectric (Pb,La)(Ti,Zr)O3 thin films on Ni and Cu foils. Relative permittivity ≈1300 and dielectric loss (tan δ) ≈0.05, leakage current density of 6.6×10-9 A/cm2, and mean breakdown field strength >2.4×106 V/cm were measured. Based on their high-field hysteresis loops, an energy density of ≈17 J/cm3 can be stored in such a capacitor at one half of its mean breakdown field. Details of processing conditions, dielectric properties, and breakdown strength will be presented.Work was supported by the U.S. Department of Energy, Office of FreedomCAR and Vehicles Technology Program, under Contract DE-AC02-06CH11357.
9:00 PM - F3.16
Investigation of the Adhesion of Electroless Copper to Glass Substrates.
Xiaoyun Cui 1 , David Hutt 1 , Paul Conway 1 Show Abstract
1 Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Leicestershire United Kingdom
Currently, device interconnect technology is being greatly improved to produce the next-generation high-density and high speed integrated circuits. However, the fabrication of matching printed circuit boards (substrates) results in manufacturing difficulties due to the reduction in metal line widths and pitches. Thin glass is a potential alternative material to manufacture multilayer substrates for flip-chip devices, instead of the traditional FR4, as it offers good dimensional stability and coefficient of thermal expansion similar to silicon. In addition, the transparency of glass makes it suitable for carrying optical signals and enables the alignment of electrical interconnects. Metallisation is a key step in the elaboration of multilayer substrates for flip-chip assembly built up from thin (100μm) glass sheets. Electroless copper deposition is an attractive method due to its relatively low cost and potential for high volume production. However, metallising the glass using electroless methods to prepare electrically conductive tracks, with sufficient thickness for solder interconnect, is challenging due to the need to activate the surface to achieve good adhesion of the copper coating which is critical for the reliability of the device. In this work, (3-aminopropyl)-trimethoxysilane (APTS) was used to pre-treat the glass, which was subsequently activated with a Pd/Sn catalyst followed by electroless copper deposition. The influence of the deposition process on the adhesion was investigated qualitatively using standard tape tests. The APTS solution and catalyst immersion times, electroless bath temperature and pH value were all controlled in order to establish the treatment parameters that enabled uniform copper deposition. In general, it was found that the APTS pre-treatment was necessary to assist in the attachment of the catalyst. Adhesion of the copper varied with catalyst immersion time: short or extended catalyst immersion times led to lower adhesion. In addition, thin copper coatings adhered well to the glass, but for layers thicker than 160 nm tape tests removed large areas. To identify the locus of failure, the fracture surfaces of copper layers peeled off the glass were examined by X-ray Photoelectron Spectroscopy (XPS) and SEM which indicated that the failure occurred between the copper and catalyst. The surface of the glass was analysed at each stage of the deposition process with particular emphasis on the influence of catalyst immersion time using XPS and Time-of-Flight Secondary Ion Mass Spectrometry. The XPS core level peaks of Pd showed that Pd(0) became stronger than Pd(II) with increasing immersion time. The presence of Pd(II) with short catalyst immersion time was indicative of PdCl2 left as residual reactant. Meanwhile, field emission SEM and atomic force microscopy were used to characterize the glass surface and Cu film structure at different stages of the deposition process for different preparation conditions.
9:00 PM - F3.17
Solution-deposited Low Voltage Zinc Oxide Transistors Using Sol-gel-derived Sodium beta-Alumina (Superionic Conductor) as Gate Dielectric.
Bhola Pal 1 , Howard Katz 1 Show Abstract
1 Material Sc. And Engineering, Johns Hopkins University, Baltimore, Maryland, United States
Sodium beta-Alumina (SBA) is a layered crystal that exhibits very high ionic conductivity in two dimensions. The ionic conductivity of SBA is due to the motion of sodium ions in lattice planes, which are separated by a distance of 11.3 Å. Between the planes there are non-conducting spinel-like blocks of Al and O ions. This kind of SBA crystal can be synthesized by sol-gel methods and subsequent heat treatment. A film of SAB can provide very high capacitance due to its highly conducting Na+ ion; while causing negligible leakage current due to the lack of electron carriers inside the crystal. A typical 70-nm-thickness SBA film has a capacitance of 300 nF/cm2. We have used this kind of film as a gate insulator for a solution-deposited n-channel ZnO field effect transistor. The film was fabricated by simple dip coating and subsequent heat treatment of a zinc acetate film. The resulting transistor needs only few volts to give considerably high drain current. The maximum field effect mobility of electrons achieved by this method is 1.0 cm2/Vs with On/Off ratio of 102.
9:00 PM - F3.18
Optimization of Solvent Casting Process of Ge23Sb7S70 Thin Films.
Shanshan Song 1 2 , Nathan Carlie 3 , Laeticia Petit 3 , Kathleen Richardson 3 , Craig Arnold 1 2 4 Show Abstract
1 Department of Electrical Engineering, Princeton University, Princeton, New Jersey, United States, 2 Princeton Institute for the Science and Technology of Matierials, Princeton University, Princeton, New Jersey, United States, 3 Advanced Materials Research Laboratory, Clemson University, Anderson, South Carolina, United States, 4 Department of Mechanical & Aerospace Engineering, Princeton University, Princeton, New Jersey, United States
Chalcogenide glasses are important low-loss mid-infrared materials, and exhibit a wide range of photo-induced phenomena and optical nonlinearities. In particular, Ge-Sb-S films have drawn attention for their high nonlinear optical properties and compositional dependencies of various optical and structural properties. In this study, we demonstrate and optimize the preparation of Ge23Sb7S70 chalcogenide thin films by solvent-casting and spin-coating techniques from liquid solutions. Four different solvents (potassium hydroxide, ammonium hydroxide, propylamine and butylamine) are tested and the dissolution kinetics of Ge23Sb7S70 and As40S60 in these solutions is studied and explained. Thin films of Ge23Sb7S70 glass are spin-coated and heat-treated under different conditions with amine-based solutions which are found to produce films with the most consistent film compositions. The film deposition process is optimized by examining the effects of the solvent, the glass to solvent ratio, the time elapsed during dissolution on the film composition, the effects of spin speed and of the annealing heat treatment on the composition of the thin film, the thickness and optical properties homogeneity over a microscope slide scale, and the effects of processing atmosphere (in air vs. inside a nitrogen-purged glove box). The film quality is examined by energy-dispersive x-ray spectroscopy (EDS), optical spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and Zygo optical profilometry. When deposited using the optimal parameters, the film is found to have a composition similar to the bulk glass and a surface roughness around 5 nm. The optical properties of the films, including refractive index and optical band gap, are found to be closely related to heat treatment conditions.
9:00 PM - F3.19
Langmuir-Blodgett Assembly of Graphite Oxide Single Layers.
Jiaxing Huang 1 , Laura Cote 1 , Franklin Kim 1 Show Abstract
1 Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States
Single layer graphite oxide is a model system for studying two dimensional membranes and has recently been recognized as a promising material for composite and electronics applications. For both the fundamental understanding of soft membrane properties and the practical applications of GO based materials, especially in a form of thin films, it is important to know how these atomically thin sheets assemble and how they interact with each other, e.g., edge-to-edge and face-to-face. Such assembly behavior can be studied using Langmuir-Blodgett technique. In addition, 2D tiling of flat graphite oxide single layers can be achieved over large areas with continuously tunable packing densities.
9:00 PM - F3.2
Highly Efficient Green Quantum Dot Based Light-Emitting Diodes.
Jeonghun Kwak 1 , Wan Ki Bae 2 3 , Seonghoon Lee 3 , Kookheon Char 2 , Changhee Lee 1 Show Abstract
1 School of Electrical Engineering & Computer Science and Inter-university Semiconductor Research Center, Seoul National University, Seoul Korea (the Republic of), 2 School of Chemical and Biological Engineering, Seoul National University, Seoul Korea (the Republic of), 3 School of Chemistry, Seoul National University, Seoul Korea (the Republic of)
Quantum dot based light-emitting diodes (QLEDs) have been investigated for several years as one of the most promising candidates for next-generation display and lighting, because colloidal nanocrystal quantum dots (QDs) have unique optical properties such as high color purity with narrow emission spectra, easy control in emission wavelength by their size, and superior luminescence efficiency in solid state compared with conjugated polymers or organic molecules. Although much progress in QLEDs have been made by controlling QD structures or optimizing device structures, QLED devices (particularly in green or blue emitting region) still suffer from low efficiency, low brightness and low color purity.In this work, we report color-saturated green QLEDs with a high efficiency of 5.2 cd/A and high color purity (above 99 % of total emission from QDs). Green QLEDs with different emission wavelengths (peak at 510 nm, 524 nm, 542 nm) were fabricated with the device structure of ITO / PEDOT:PSS / poly-(N,N’-bis(4-butylphenyl)-N,N’-bis(phenyl)benzidine) (poly-TPD) / QDs / 1,3,5-tris(N-phenylbenzimidazol-2,yl) benzene (TPBI) / LiF / Al. They showed excellent performances such as low turn on voltage (3.5 V), the maximum brightness above 10,000 cd/m2, and narrow spectral bandwidth (FHWM < 30 nm) without parasitic emission originating from the organic layers proximal to the QD layer (i.e., poly-TPD or TPBI). We attribute these performances to the chemical composition gradient structure of QDs as well as the uniform and high surface coverage of the QD layer.
9:00 PM - F3.20
Polycrystalline Thin Film FeS2 Pyrite Produced via Post Deposition Anneal of Spin Coated Iron Hydroxo-nitrate and Hydroxo-oxalate.
Heather Platt 1 , Stephen Meyers 1 , Jeremy Anderson 1 , Douglas Keszler 1 Show Abstract
1 Chemistry, Oregon State University, Corvallis, Oregon, United States
FeS2 pyrite is a moderate band gap semiconductor with an optical absorption coefficient on the order of 105 cm-1. These properties, along with the low cost and benign nature of the constituent elements, make it an attractive candidate for the absorber layer of a solar cell. Small open circuit voltages obtained from thin films have limited development, however. To examine the prospects for production of high quality polycrystalline FeS2 films, we have deposited smooth amorphous iron hydroxo-nitrate and hydroxo-oxalate films from unique aqueous precursors and converted them under flowing H2S(g). In this contribution, we describe the deposition methodology and optical, electrical, and morphological characterization of the resulting FeS2 pyrite films.
9:00 PM - F3.21
Microstructure Dependence of Liquid-Phase Deposited SiO2 Films on Solution Parameters.
Shijun Yu 1 , Junghyun Cho 1 Show Abstract
1 Dept. of Mechanical Engineering & Materials Science and Engineering Program, State University of New York (SUNY) at Binghamton, Binghamton, New York, United States
The advantage of near room temperature processes and self-fluorinated characteristics makes liquid-phase deposited SiO2 films as a promising interlayer dielectric. Several research groups reported inconsistent results for SiO2 deposition rates with boric acid addition to the precursor solution, but little work has focused on microstructure differences. In this study, using a supersaturated hydrofluosilicic acid (H2SiF6) aqueous solution ranging from 0.5M to 2M, a series of SiO2 films were deposited both on FTO-coated glass and piranha pretreated silicon, with controllable thicknesses between 50 nm and 1 um. It was observed that these films change from very smooth surface to particle agglomerated porous morphologies as the concentration of boric acid in the solution increases. In parallel, the effect of H2SiF6 concentration and solution temperature on film microstructures was also explored. One goal of this study is to identify an underlying mechanism that can explain the thin film formation involving nucleation, growth, and agglomeration of the SiO2 nanoparticles. Furthermore, the effect of deposition conditions on the porosity and the fluorine content in the films and their influence on dielectric performance are investigated.
9:00 PM - F3.22
Flexible Complementary Inverters Based on Solution-processable Inorganic Nanocrystals.
Jaewon Jang 1 , Junggwon Yun 1 , Kyoungah Cho 1 , Byoungjun Park 1 , Sangsig Kim 1 Show Abstract
1 , Korea University, Seoul Korea (the Republic of)
Complementary inverters were fabricated on flexible plastic substrates using solution-based bottom-up strategies. A complementary inverter was constructed with an p-channel HgTe nanocrystal (NC)-based thin film transistor (TFT) used as the load and a n-channel HgSe NC-based TFT used as the driver. The load TFT exhibited a field effect mobility of 0.7 cm2/Vs and an on/off current ratio of ~103. On the other hand, the driver TFT possessed a field effect mobility of 4.0 cm2/Vs and an on/off current ratio of ~102. The fabricated device acted as a typical inverter with the high output state which was over 90% of the full voltages at a low input voltage of 0 V and the low state at a high input voltage of + 5 V. The complementary inverters possessed logic gains of 12~18, a logic swing of 90% and a noise margin (NM) of 2.5 V corresponding to 0~5 V input voltages. The effect of bending strain on electrical characteristics of the complementary inverters was also investigated. The tensile or compressive strain of 0.2% did not affect the electrical characteristics of our devices. When the substrate was subjected to a tensile or compressive strain of 0.7%, the representative complementary inverter revealed the gains of 11~13 and 15~19 at VDD of +15 V and +20 V, respectively. In spite of external tensile or compressive strain, it still showed a high logic swing over 90% and a NM of 2.5 V.
9:00 PM - F3.23
Low-temperature Growth of Uniform ZnO Particle with Controllable Morphologies.
Ming Da Yang 1 , Mean Jue Tung 1 Show Abstract
1 , Industrial Technology Research Institute, Hsinchu, Taiwan Taiwan
9:00 PM - F3.24
Magnetic and Metallic Nanoparticle Arrays Prepared Through Spin Casting.
Joseph Tracy 1 , Aaron Johnston-Peck 1 , Junwei Wang 1 Show Abstract
1 Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina, United States
Spin casting is an economical method for depositing monolayer and multilayer arrays of ligand-protected nanoparticles (NPs) formed through self-assembly. We have investigated the self-assembly process during spin casting by varying different parameters, including substrate functionalization, solvents, spin speeds, concentrations, and core sizes of metallic (Au) and magnetic (FePt and Ni) NPs. The local ordering, defects, and grain boundaries in these NP arrays have been characterized using electron microscopy. We will also report optical measurements for assessing surface plasmon resonance coupling in arrays of Au NPs and magnetic characterization of dipolar coupling in arrays of magnetic NPs.
9:00 PM - F3.25
Trade-off Between Permittivity and Reliability in BaTiO3-Based Thin Film Capacitors.
Song Won Ko 1 , Clive Randall 1 , Susan Trolier-McKinstry 1 , Michael Randall 2 , Tony Kinard 2 , Uwe Meier 2 , Philip Lessner 2 Show Abstract
1 , Pennsylvania State University, University Park, Pennsylvania, United States, 2 , KEMET Electronics Corporation, Simpsonville, South Carolina, United States
9:00 PM - F3.26
Preparation of Smooth Zinc Oxide Thin Film via Liquid Phase Reaction with Cation Additives.
Takeyasu Saito 1 , Yoshihisa Hirata 1 , Naoki Okamoto 1 , Kazuo Kondo 1 Show Abstract
1 Chemical engineering, Osaka Prefecture University, Sakai Japan
Zinc oxide (ZnO) is a very attractive material as transparent, cheap, stabile semiconductor as well as conductive layers. ZnO films are generally synthesized by dry methods like chemical vapor deposition, sputtering and pulsed laser deposition. However, thin films fabrication from liquid phase could offer a lot of advantages such as simplicity, low cost, large area growth and high throughput. In this study, the effects of positive ions in a solution such as Mg, Ga and Al on film morphology and crystallographic structure were investigated. Slide glass (76mm×26mm×1t), the Si (100) (10mm sq.) and Si (100) with 1um-thick thermal oxide (10mm sq.) were employed as substrates. Nucleation procedures were carried out by dipping in the solutions, SnCl2: 0.1 mol/l → AgCl: 0.1 mol/l → PdCl2: 0.1 mol/l for 10 minutes each. The substrates were hold in a solution of Zn(NO3)2: 0.1 mol/l and dimethylamine-borane (DMAB): 1E-2 to 0.1 mol/l in a range of 60-80°C for four hours. Mg(NO3)2, Ga(NO3)3 or Al(NO3)3 in a range from 1E-4 to 5E-2 mol/l were added as a cation source. Surface and cross-section of ZnO films were observed by FE-SEM and crystallographic structure was determined by X-ray diffraction. The dependency of the DMAB concentration and reaction temperature was investigated and a solution with Zn(NO3)2: 0.1 mol/l and DMAB: 0.05 at 70°C was found to be suitable for continuous film growth with hexagonal ZnO structure, where the growth rate was 0.13um/h. This condition was set as the standard to investigate the effects of cation additives. In the case of Al(NO3)3: 1E-2 mol/l addition, the formation of continuous films was recognized, however the peak of ZnO is not detected, which suggests that the films is amorphous or microcrystalline and that the Al ion beyond a certain amount results in obstructing crystallization of ZnO. On the other hand, a strong peak of ZnO could be recognized when Al(NO3)3 concentration was equal to or less than 1E-3 mol/l, and also the film surface became flat possibly due to the increase of the nucleation density. In the case of Ga(NO3)3 addition, the trend was almost the same compared with the Al(NO3)3 addition except the surface flatness. In the case of Mg(NO3)2 addition, a peak of ZnO was recognized in all the concentration studied here and surface morphology did not change. Compared with the cases with 1E-4 mol/l cation additition, the growth rates with Mg, Ga and Al addition were 0.13um/h, 0.38um/h and 0.35um/h., respectively. The growth rate was enhanced by 1E-4 mol/l of Ga or Al addition. In summary, a solution with Zn(NO3)2: 0.1 mol/l and DMAB: 0.05 at 70°C offered continuous and hexagonal ZnO thin films with the growth rate of 0.13um/h. By adding 1E-4 mol/l of Ga or Al, the growth rate became three times compared with the case without cation and particularly the surface morphology became flat in the case of Al.
9:00 PM - F3.27
CaBi4Ti4O15 Thin Film Deposition on Electroplated Platinum Substrates using a Sol-gel Method.
Takeyasu Saito 1 , Yuichiro Hirota 1 , Naoki Okamoto 1 , Kazuo Kondo 1 , Takeshi Yoshimura 2 , Norifumi Fujimura 2 Show Abstract
1 Chemical engineering, Osaka Prefecture University, Sakai Japan, 2 Physics and Electronics , Osaka Prefecture University , Sakai Japan
Ferroelectric random access memory (FeRAM) has drawn great attention as one of promising nonvolatile, low operating power, high write speed, and high write endurance device candidates. However, 3-D capacitor-integration technology for larger memory size as well as more robust materials without lead for high temperature operation are the recent important issue. In this work, CaBi4Ti4O15 growth on different Platinum substrates was carried out through a sol-gel method. The effects of crystallization procedures, bismuth concentration on surface morphology and crystallographic structure were investigated. Each of Ca, Bi, Ti containing solution (0.5M/l, Kojyundo Chemical Co, Japan) was employed as a metal source. Three kinds of Pt substrates were used. The first one is the highly oriented sputtered Pt(111) (200nm) substrates without Pt(200) orientation, the second is the sputtered Pt with weak Pt(200) orientation and the third is electroplated Pt (500nm) substrates on sputtered Pt with weak Pt(200) orientation. The ratio of Ca, Bi and Ti was 1, 4 and 4 or 1, 4.8 and 4. The mixed solutions were spin-coated on substrates, followed by a drying process at 120°C for 2 min. The calcination was carried out at 300-400°C for 10 min and then rapid thermal annealing (RTA) at 650-800°C for 10 min was also done in ambient atmosphere. The surface of film was observed by FE-SEM and the crystallographic structure was determined by an X-ray diffraction. Both RTA temperature and excess amount of Bi have an effect on the surface morphology and crystallographic structure. Higher RTA temperature up to 800°C decreased Pyrochlore contents in the films and 20% excess amount of Bi also decreased the contents. The crystalline diameter measured by FE-SEM became larger with increasing RTA temperature from 650-750°C and then remained almost the same at 750 and 800°C. CaBi4Ti4O15 crystallographic structure grown on the highly oriented sputtered Pt(111) substrates has a strong (119) peak and it was the main. However, CaBi4Ti4O15 crystallographic structure on sputtered Pt with weak Pt(200) orientation and that on electroplated Pt (500nm) substrates has several peaks ascribed to c-axis orientation. The reasons for the difference are now under study. In summary, higher RTA temperature and 20% excess amount of Bi decreased Pyrochlore contents in the deposited films. C-axis oriented CaBi4Ti4O15 thin film could be grown on platinum substrates with weak Pt(200) orientation.
9:00 PM - F3.3
Electrophoretic Deposition: An Effective Technique for the Production of Transparent and Luminescent Films of Rare-Earth Sesquioxide (RE2O3) Nanocrystals.
Sameer Mahajan 1 2 , Justine Hart 3 , James Dickerson 2 3 Show Abstract
1 Interdisciplinary Program in Materials Science, Vanderbilt University, Nashville, Tennessee, United States, 2 Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, United States, 3 Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, United States
Numerous solution-based synthesis techniques have been developed to fabricate nanocrystalline structures. Integration of these structures into next-generation devices requires them to be distributed into thin film form via low-cost, high throughput techniques. Electrophoretic deposition (EPD) of nanomaterials offers significant control over the thickness, homogeneity, and site selectivity of the thin film. This approach also provides low-cost and high throughput in the film formation. Here, we report the successful deposition of homogeneous and transparent films of sub-3 nm europium sesquioxide (Eu2
), terbium sesquioxide (Tb2
), and gadolinium sesquioxide (Gd2
) nanocrystals via EPD. Eu2
, and Gd2
are known for their characteristic red and green emission colors arising from Eu3+
ions, respectively. Such materials and their derivatives can be employed in video displays, luminescent biological tags, and light emitting devices in their film form.
The nanocrystals, employed for the film deposition, were synthesized via hot solution phase method and purified with ethanol prior to deposition. The nanocrystals were dispersed in hexane, which facilitated formation of stable dispersion. The films were deposited from the nanocrystal dispersion in presence of high electric field (~ 2-4 kV/cm). The transparent films of the nanocrystals formed on both of the electrodes, anode and cathode. The film roughness was determined with atomic force microscopy (AFM) and film morphology was investigated using scanning electron microscopy (SEM) and optical microscopy. Energy dispersive spectroscopy (EDS) of the film confirmed film deposition on variety of conductive substrates. Film thickness measurements were performed using profilometry. Optical characterization of films was performed with absorption and photoluminescence spectroscopy.
ReferencesS. Shionoya, W. M. Yen, Phosphor Handbook, CRC Press, Boca Raton 1999S. V. Mahajan, J. H. Dickerson, Nanotechnology 2007.
9:00 PM - F3.4
Preparation of Highly Luminescent Semiconductor Nanocrystals and Their Application to Light-Emitting Diodes.
Wan Ki Bae 1 , Jeonghun Kwak 3 , Changhee Lee 3 , Seonghoon Lee 2 , Kookheon Char 1 Show Abstract
1 School of Chemical and Biological Engineering, Seoul National University, Seoul Korea (the Republic of), 3 School of Electrical Engineering and Computer Science, Seoul National University, Seoul Korea (the Republic of), 2 School of Chemistry, Seoul National University, Seoul Korea (the Republic of)
Great efforts have been placed on the preparation of colloidal semiconductor nanocrystals (NCs) not only for fundamental studies in nanoscopic materials but also for their potential applications to light-emitting diodes, photovoltaic devices, and biomarkers. Owing to the recent advances in structural design and synthetic procedure of NCs, huge progress has been achieved for useful applications, particularly in light emitting systems even down to practical levels. However, those achievements in the synthesis and applications of NCs reported so far are mostly limited to red emitting NCs.In this work, we present the synthesis of highly efficient green and blue emitting NCs in reproducible and straightforward manner. For green emitting NCs, CdSe@ZnS structures with chemical composition gradient are designed and prepared by the single-step synthesis based on reactivity difference between Cd and Zn or Se and S precursors. For blue emitting NCs, Cd1-xZnxS@ZnS structures with diffuse interface between the core (Cd1-xZnxS) and the shell (ZnS) phase were realized with the one-pot synthesis method in gram-scale. Both prepared NCs exhibit narrow spectral bandwidth (FHWM < 30 nm), high photoluminescence efficiency (up to 80 %), and photo- and colloidal stability. We also demonstrate highly efficient electroluminescent devices based on NCs (EQE above 1.5 %, maximum luminescence above 10,000 cd/m2).
9:00 PM - F3.5
Photocatalytic Oxidation of Surfactants for the Patterned Deposition of Nanoparticles onto Metal Oxide Surfaces.
David Watson 1 , Gregory Soja 1 Show Abstract
1 , University at Buffalo, Buffalo, New York, United States
The patterned deposition of nanoparticles onto substrate surfaces may enable applications in array-based sensors and electronic, photonic, and magnetic devices. One promising fabrication strategy involves the combination of top-down and bottom-up methods. Techniques such as monolayer photolithography, scanning probe lithography, and microcontact printing are used to produce patterned, monolayer-functionalized surfaces, which serve as templates for nanoparticle adsorption. Top-down patterning imparts long-range order, while bottom-up assembly enables control over the connectivity between nanoparticles and the substrate surface.We have developed a solution-phase photolithographic method for the patterned deposition of metallic and semiconducting nanoparticles onto nanocrystalline TiO2 films. The nanoparticles are adsorbed to TiO2 surfaces through bifunctional mercaptoalkanoic acid (MAA) linkers. The color and optical density of the films are tunable by varying the composition and coverage of surface-adsorbed nanoparticles. The photopatterning mechanism involves the TiO2-catalyzed oxidative degradation of surface-adsorbed MAAs, prior to nanoparticle adsorption. Nanoparticles adsorb only to unilluminated regions of the substrate. Illumination through a photomask, under ambient conditions, yields optically patterned surfaces with diffraction-limited resolution. The high surface area of the nanocrystalline TiO2 substrates enables the adsorption of nanoparticles at high surface coverages, leading to optically dense patterns.This presentation will focus on mechanistic aspects of the monolayer photolithography and self-assembly processes. First, we will discuss the influence of surfactant structure, composition, and functionalization on the assembly of monolayers on metal oxide surfaces. Specifically, we will focus on the influence of intermolecular interactions within monolayers on surface attachment reactions, monolayer composition, and the affinity of metallic and semiconducting nanoparticles for monolayer-functionalized surfaces. Second, we will discuss the influence of surfactant structure and functionalization on the kinetics, mechanism, and efficiency of TiO2-catalyzed photooxidation reactions. Our findings lend insight into the mechanisms of TiO2-catalyzed photochemical reactions and reveal optimal conditions for the solution-phase patterned deposition of nanoparticles onto metal oxide surfaces.
9:00 PM - F3.6
Self Assembly Techniques for Fabrication of Composite Isotropic Optical Negative Index Metamaterials.
Joel Therrien 1 , Alkim Akyurtlu 1 , Aaron Bandremer 2 Show Abstract
1 Electrical and Computer Engineering, U. of Massachusetts Lowell, Lowell, Massachusetts, United States, 2 Biomedical Engineering and Biotechnology, U. of Massachusetts at Lowell, Lowell, Massachusetts, United States
Techniques for the fabrication of novel optical metamaterials using synthetic chemistry and biological self assembly will be presented. Recently, a novel low-loss and isotropic negative index metamaterial (NIM) design for the visible regime based on silicon carbide (SiC) spherical nanoparticles embedded inside of a MgB2 host has been developed (A. G. Kussow, et al., Physical Review B, 76, 195123, 1-7, 2007). Design parameters of this material are the sizes and fill factor of the SiC nanoparticles. The latter factor also defines the distance between the SiC nanospheres within the host. The main challenge in making such a material lies in the precise placement of the SiC nanoparticles and the avoidance of nanoparticle clustering. Hence, the main goal of this work is to embed SiC nanoparticles at pre-defined distances in the MgB2 matrix. A well-controlled surface modification of SiC nanoparticles will be used to fabricate the desired material. One approach will be the adaptation of methods for the functionalization of silicon nitride (SiN) using alkenes with double functional groups (A. Arafat, et al., JACS, 126, 8600-8601, 2004). We have investigated a 11-carbon alkene with bromine functional end for incorporation into our NIM. Bromine functionalization was verified by XPS, however, thiol substitution using sodium hydrosulfide was discouraging. A bifunctional polyethylene glycol (PEG) with maleimide and silane groups was subsequently investigated. SiC was functionalized with a thiol group and bonded to the maleimide group of the PEG, while the silane group was bonded to a glass substrate used in NIMs functional testing.We will also report on the progress of using biological self assembly for the placement of SiC nanoparticles. We have used phage display to screen for peptides that bind with specificity to the nanoparticles and glass substrates used in testing (S. Whaley, et al., Nature, 405, 665-668, 2000). M13 phages were genetically engineered to display peptides binding the SiC on one terminus of the M13 and the glass substrate at the other terminus with a defined phage length.Difficulties in fabricating this device include adapting SiN chemistry to SiC, verifying functionalization and engineering M13 phage for the biological self assembly approach. The fabrication methods are evaluated using SEM and AFM to determine particle spacing. Once the desired spacing is obtained, MgB2 will be deposited via sputtering. This process will be repeated for two layers of the MgB2/SiC material to obtain the final NIM design. The material will then be characterized using transmission spectra and XRD.
9:00 PM - F3.7
Deposition of Nanostructured Thin Films by Microreactor-Assisted Chemical Processes.
Seung-Yeol Han 1 , Changho Choi 1 , Ana Putnam 1 , Chih-Heng Tseng 2 , Brian Paul 2 , Si-Ok Ryu 3 , Tae-Jin Lee 3 , Chih-hung Chang 1 Show Abstract
1 Chemical Engineering, Oregon State University, Corvallis, Oregon, United States, 2 Industrial and Manufacturing , Oregon State University, Corvallis, Oregon, United States, 3 , Yeungnam University, Daedong, Gyeongsan, Korea (the Republic of)
Nanostructured thin films were deposited by microreactor-assisted chemical processes. This technique uses continuous flow microreactors for the synthesis and deposition of nanomaterials. In synthesis, microreactor technology offers large surface-area-to-volume ratios within microchannel structures to accelerate heat and mass transport. This accelerated transport allows for rapid changes in reaction temperatures and concentrations leading to more uniform heating and mixing in the deposition process. Consequently, microreactors have been demonstrated to yield dramatic enhancements in controlling the quantum dot size distributions, thereby minimizing particle size variability. The possibility of synthesizing nanomaterials in the required volumes at the point-of-application eliminates the need to store and transport potentially hazardous materials, while providing new opportunities for tailoring novel nanostructures and nanoshaped features. Microreactors have been found to radically improve cycle times and yields associated with the production of a broad range of materials including both inorganic and organic materials that cover a variety of applications such as dendrimers, functionalized metal nanoclusters, metal oxide semiconductor nanoparticles. In particular, we have used microreactors to dispense reactant streams directly onto moving or stationary substrates to yield nanostructured thin films. Results-to-date demonstrate the possibility to control the reacting flux including small intermediate-reaction molecules, macromolecules, nanoclusters, nanoparticlse, and structured assemble of nanoparticles directly after synthesis. These results also suggest the possibility of producing many types of nanostructured films using low cost solution chemistry. In this paper, we will report various examples of MAND.
9:00 PM - F3.8
Self Organized TiO2 Nanoparticles and SWNT Composite for Gate Dielectric of a Flexible Organic Thin Film Transistor (OTFT).
Himadri Acharya 1 , Jinwoo Sung 1 , Tae Hee Kim 1 , Byung Gil Min 2 , Cheolmin Park 1 Show Abstract
1 Department of Materials Science and Engineering, Yonsei University , Seoul Korea (the Republic of), 2 School of Advanced Materials and System Engineeing, Kumho Institute of Technology, Kumi Korea (the Republic of)
9:00 PM - F3.9
Binding Characteristics of Surface Ligands on PbSe QDs and Impact on Conductivity.
Won Jin Kim 1 , Sung Jin Kim 1 2 , Jang Won Seo 1 , Alexander Cartwright 1 2 , Paras Prasad 1 2 3 Show Abstract
1 Institute for Lasers, Photonics and Biophotonics, University at Buffalo, State University of New York, Buffalo, New York, United States, 2 Electrical Engineering, University at Buffalo, State University of New York, Buffalo, New York, United States, 3 Chemistry, University at Buffalo, State University of New York, Buffalo, New York, United States
David B. Mitzi IBM T. J. Watson Research Center
David Ginley National Renewable Energy Laboratory
Bernd Smarsly Justus Liebig University Giessen
Dmitri V. Talapin The University of Chicago
F4: Porous and Structured Films
Wednesday AM, December 03, 2008
Room 208 (Hynes)
9:30 AM - **F4.1
Evaporation Induced Self-Assembly of Porous and Composite Nanostructures.
C. Jeffrey Brinker 1 2 Show Abstract
1 Self-Assembly Department, Sandia National Laboratory/UNM, Albuquerque, New Mexico, United States, 2 Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico, United States
10:00 AM - F4.2
Free-standing and Patternable Monolayer Nanoparticle/polymer Arrays Formed by Evaporation Induced Self-assembly at a Fluid Interface.
Shisheng Xiong 1 , Jiebin Pang 1 , Darren Dunphy 1 , Jeffrey Brinker 1 2 Show Abstract
1 Department of Chemical Engineering, University of New Mexico, Albuquerque, New Mexico, United States, 2 Advanced Material Laboratory, Sandia National Laboratories, Albuquerque, New Mexico, United States
Ordered nanoparticle (NP) monolayers are of fundamental interest as 2D artificial solids in which electronic, magnetic, and optical properties can be tuned through electron charging and quantum confinement of individual NPs mediated by coupling interactions with neighboring NPs. Recently, we have developed a universal, fast and facile method to prepare robust and transferable monolayer nanoparticle arrays by evaporation-induced self-assembly at a fluid interface (JACS 2008). As-synthesized hydrophobic NPs were assembled on a water interface from toluene containing polymethylmethacrylate (PMMA). In this case solvent evaporation concentrates the thinning film in NPs and PMMA, leading to NP self assembly and solidification into an ordered NP/polymer nanocomposite monolayer with physical dimensions of up to 10 cm2. The NP/PMMA monolayer can be transferred to arbitrary substrates and remains stable as a freestanding membrane suspended over cm-sized holes-even with free edges. Moreover, the PMMA serves as a photoresist enabling two modes of electron beam (e-beam) NP patterning. In combination these extensions contribute to the ability to integrate NP arrays into robust micro- and macroscale devices. Au NP/PMMA and CdSe QD/PMMA films transferred to glass slides or silicon wafers have been characterized with UV-vis spectroscopy and photoluminescence spectroscopy, respectively. The electron transport behavior of Au NP arrays with PMMA dielectric spacers is under investigation.
10:15 AM - F4.3
Formation of Controlled Alumina Films using Deposition in Supercritical Fluids for Electronic and Telecommunication Devices.
Cyril Aymonier 1 2 , Mélanie Majimel 1 2 , François Cansell 1 2 , Catherine Elissalde 1 , Mario Maglione 1 , Jean-François Sylvain 1 , Jean-Marc Heintz 1 Show Abstract
1 ICMCB-Supercritical Fluids, CNRS, Pessac Cedex France, 2 ICMCB-ENSCPB-Supercritical Fluids, Université de Bordeaux, Pessac Cedex France
Alumina is the most widely used oxide ceramic material for many applications in electronics, aeronautics, high temperature metallurgy or biomedicine thanks to its interesting mechanical, thermal, electrical and chemical properties . Even if it is a well known system, it remains challenges, especially the one for obtaining dense nanostructured alumina-based ceramics at low temperatures. We recently showed that the sintering of alumina can be optimized by playing on the cristallinity and structure of the initial material . This can be controlled with the elaboration in different sub- and supercritical media: the transformation of Al(acac)3 precursor in a supercritical CO2/EtOH mixture leads to the synthesis of an amorphous alumina and in a subcritical H2O/EtOH mixture to boehmite. This works has highlighted a decrease of the sintering temperature by using the amorphous alumina powder as starting material in comparison with the use of the boehmite starting powder. This very interesting result can then be applied to the deposition of alumina layers on different kinds of particles or substrates, as an alternative deposition method to CVD or still ALD . We propose to focus this presentation on the chemistry in supercritical fluids applied to the controlled deposition of alumina films on two kinds of substrates:- i) on copper plates used as heat sinks in electronics : in this system, alumina represents a good compromise between thermal conductivity and electrical insulation. The challenge is to form dense alumina films below the melting temperature of copper,- ii) on ferroelectric nanoparticles used as powder for ceramics capacitor in telecommunications : the core@shell nanoparticles act as nanobricks to build new nanostructured composite ceramics keeping interesting dielectric properties (high permittivity and low losses). We will discuss the influence of the main operating parameters of the supercritical fluid chemical deposition process, especially the influence of reaction media, on the characteristics of the alumina film (micro/nanostructure, thickness, interface properties …). We will also present the properties of the obtained devices.References: E. Dörre and H. Hübner, Alumina – Processing, properties and applications, Springer-Verlag, Berlin, 1984 C. Bousquet, C. Elissalde, C. Aymonier, M. Maglione, F. Cansell, J.M. Heintz, Tunability of Al2O3 crystallinity using supercritical fluid media: effect on sintering, J. Eur. Ceram. Soc., 2008, 28, 223-228. C. Aymonier, A. Loppinet-Serani, H. Reverón, Y. Garrabos, F. Cansell, Review of Supercritical Fluids in Inorganic Materials Science, J. Supercrit. Fluids, 2006, 38, 242-251. P.M. Geffroy, D. Mathias, J.F. Silvain, Heat sink material selection in electronic devices by computational approach, Advanced Engineering Materials, 2008, 10 (4), 400-405 C. Bousquet, F. Cansell, C. Elissalde, M. Maglione, C. Aymonier, manuscript in preparation.
10:30 AM - **F4.4
Synthesis of Nanostructured ZnO Thin Films via Low Temperature Aqueous Deposition.
Yun-Ju Lee 1 , David Scrymgeour 1 , Dana Olson 2 , Matthew Lloyd 1 , Erik Spoerke 1 , James Voigt 1 , Julia Hsu 1 Show Abstract
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 , National Renewable Energy Laboratory, Golden, Colorado, United States
Single crystalline ZnO nanorod arrays (NRAs) represent promising nanostructures for electronic and photonic devices due to properties such as excellent electron mobility, high exciton binding energy, and large area, low temperature fabrication. In the last several years, we have demonstrated the synthesis of ZnO NRAs with highly tunable morphologies and properties using controlled precipitation of ZnO from aqueous solutions. In this talk, I describe the synthesis of various nanostructured thin films based on ZnO NRAs and demonstrate their potential applications in photovoltaics and photonics. First, by changing the seeding and NRA growth parameters, the alignment and dimensions of the ZnO nanorods are systematically varied. Such changes in NRA morphology correlate strongly to differences in the current-voltage response and power conversion efficiency of hybrid conjugated polymer-ZnO NRA photovoltaic devices. Second, with the addition of organic growth modifier, the degree of nanorod tip tapering can be carefully tuned. The resulting textured films with graduated refractive index profiles demonstrate broadband antireflection response in good agreement with theoretical models. Third, the surface of ZnO NRAs is modified after synthesis with conformal coatings of thin inorganic films such as TiOx, which affect open-circuit voltage in solar cells by decreasing carrier recombination. Finally, using codeposition of Zn and appropriate dopant ions in aqueous solution, ZnO NRAs with controlled dopant incorporation are demonstrated. These doped NRAs exhibit changes in electrical properties consistent with dopant type and concentration, and may prove useful in a variety of applications. Other modifications in the morphology and properties of nanostructured thin films based on ZnO NRAs will also be discussed.This project is financially supported by the LDRD program at Sandia National Laboratories. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.
11:00 AM - F4: Meso
11:30 AM - **F4.5
Soft Chemistry Based Routes to Nanostructured Inorganic and Hybrid O-I Thin Films.
Clement Sanchez 1 , Cedric Boissiere 1 , Christel Laberty 1 , David Grosso 1 , Lionel Nicole 1 Show Abstract
1 CHEMISTRY LCMCP UMR 7574, CNRS-University of PARIS VI, Paris France
Considerable effort is being currently directed to the obtention of nanostructured hybrids and transition metal oxides based materials. The use of sol-gel chemistry with or without ordered lyotropic phases as templating agents is a low cost, versatile and convenient way to produce smart functionnal thin films. The control of the nanostructuration, domain sizes, and cristallisation of these sol-gel derived coatings is of paramount importance to be able to tune the resulting properties of the final materials. This conference will present the major advances we have recently performed in the field of sol-gel derived inorganic or hybrid thin films. Some examples concerning the design of inorganic metal oxides and hybrid materials processes as thin films and some of our results concerning membranes having hierarchical structures will be presented. New films and membranes that act as sensors, photocatalysts, conductive membranes and low-k materials will be described.Recent review articles*Design, Synthesis, and Properties of Inorganic and Hybrid Thin Films Having Periodically Organized Nanoporosity. C. Sanchez, C. Boissière, D.Grosso, C. Laberty, and L. Nicole, Chem. Mater. 2008, 20, 682–737, *Applications of hybrid organic–inorganic nanocomposites, C. Sanchez, B. Julian , P. Belleville and M. Popall, J. Mater. Chem., 2005, 15, 3559, *Inorganic and Hybrid Nanofibrous Materials Templated with Organogelators, M. Llusar and C. Sanchez, Chem. Mater. 2008, 20, 782, *Photonic and nanobiophotonic properties of luminescent lanthanide-doped hybrid organic–inorganic materials.P. Escribano, B. Julian-Lopez, J. Planelles-Arago, E. Cordoncillo, B. Viana, C. Sanchez, J. Mater. Chem., 2008, 18, 23 , *Biomimetism and bioinspiration as tools for the design of innovative materials and systems C. Sanchez, H. Arribart, MM Giraud-Guille. Nature Materials, 2005, Vol 4 , p277.*Mechanical properties of hybrid organic-inorganic materials, F. Mammeri, E. Le Bourhis, L. Rozes, C. Sanchez, . Mater. Chem., 2005, 18, 23.
12:00 PM - F4.6
Nanostructured Metal Oxide and Composite Electrodes for Use in Ultracapacitors.
Michael Brumbach 1 , Bruce Bunker 1 3 , Bonnie McKenzie 2 Show Abstract
1 Electronic and Nanostructured Materials, Sandia National Laboratories, Albuquerque, New Mexico, United States, 3 Center for Integrated Nanotechnology, Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 Materials Characterization, Sandia National Laboratories, Albuquerque, New Mexico, United States
Ultracapacitors, or electrochemical capacitors, are known to achieve very high specific capacitances by storing charge in the electrical double layer at the electrode/electrolyte interface where the charges are separated over very short distances. Additionally, charge storage can be accomplished via surface adsorption and/or via redox processes within the bulk electrode. Maximizing power densities and other desired properties of ultracapacitors requires configuring redox-active materials in specific architectures that: 1) maximize electrolyte-electrode contact area, 2) minimize transport distances for both electrons and charge compensating species such as protons, and 3) minimize transport barriers via inclusion of conducting material. We have developed a range of simple solution-based processing methods that enable us to systematically vary the compositions and architectures of multi-component composites at the nano-scale. We have studied the role of architecture on charge storage by using nanocomposites containing electrochemically inert network formers such has TiO2 and Nb2O5. RuO2 functions as the electroactive material while polymeric species can function to direct nanostructure formation and/or to provide conductive pathways. The electrochemical performance of the resulting nano-structured electrodes has been characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The results indicate that these additions have a dramatic effect on improving the performance relative to the base-line material. Mechanisms of the performance boost will be discussed in terms of both composition and architecture as determined via XPS, electron microscopies, FTIR, and a range of other characterization methods.
12:15 PM - F4.7
A Simple Solution-Based Method for Depositing Conductive Nanoscale-Coatings of RuO2 onto SiO2 Filter Paper: Obtaining Macroscopic Conductivity from Nanostructured Features.
Christopher Chervin 1 , Alia Lubers 1 , Jeffrey Long 1 , Justin Lytle 1 , Mark Westgate 2 , Katherine Pettigrew 1 , John Fontanella 2 , Debra Rolison 1 Show Abstract
1 Surface Chemistry Branch, Naval Research Laboratory, Washington, District of Columbia, United States, 2 Department of Physics, U.S. Naval Academy, Annapolis, Maryland, United States
Wednesday, 12/3New Presentation Time and Paper NumberF4.8 @ 11:30 PM to F4.7 @ 11:15 PMA Simple Solution-Based Method for Depositing Conductive Nanoscale-Coatings of RuO2 onto SiO2 Filter Paper: Obtaining Macroscopic Conductivity from Nanostructured Features.Christopher Chervin
12:30 PM - F4.8
Nanocrystalline Photonic Crystalline Supports as Photoanodes for Water Oxidation.
Nathan Neale 1 , Arthur Frank 1 , Arthur Nozik 1 Show Abstract
1 , National Renewable Energy Laboratory, Golden, Colorado, United States
Wednesday, 12/3New Presentation Time and Paper NumberF4.9 @ 11:45 to F4.8 @ 11:30 PMNanocrystalline Photonic Crystalline Supports as Photoanodes for Water Oxidation. Nathan Neale
F5: Printing, Lithography, Patterning
Wednesday PM, December 03, 2008
Room 208 (Hynes)
2:30 PM - **F5.1
Develop Printable Solution Processes for Inorganic Semiconductors.
DooHyoung Lee 1 , Yu-Jen Chang 1 , SeungYeol Han 1 , Wei Wang 1 , Yu-Wei Su 1 , Gregory Herman 2 , Wei-Fang Su 3 , Chih-hung Chang 1 Show Abstract
1 Chemical Engineering, Oregon State University, Corvallis, Oregon, United States, 2 , Sharp Laboratories of America, Camas, Washington, United States, 3 Materials Science and Engineering, National Taiwan University, Taipei Taiwan
Current methods for the production of functional inorganic electronic devices are based on the sequential deposition, patterning, and etching of selected semiconducting, conducting, and insulating materials. These sequential processes generally involve multiple photolithography and vacuum deposition processes, which contribute to their high manufacturing costs. Solution-based and direct printing of inorganic materials offer the possibility of depositing high quality thin films at low temperature under atmospheric conditions, and the direct additive patterning processes that enable the fabrication of high-performance and ultra-low-cost electronics. Over the last few years, there has been tremendous progress on direct inkjet printing of polymer TFTs. Inkjet printing of inorganic materials is relatively rare compared to the inkjet printing of organic materials, especially for semiconductor materials. Recently, we have developed a simple and general route to form high performance inorganic electronic materials that is suitable for inkjet printing. We have printed a variety of electronic materials including conductors, semiconductors, insulators, and luminescent materials. In this paper, we will report our progress in this area.
3:00 PM - F5.2
Sol-Gel Inks for Direct-Write Assembly of Micro-Periodic Oxide Structures for Photonic and Sensor Applications.
Eric Duoss 1 2 , Mariusz Twardowski 1 2 , David Lorang 1 2 , Avner Rothschild 3 , Harry Tuller 4 , Jennifer Lewis 1 2 Show Abstract
1 Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 3 Materials Engineering, Technion – Israel Institute of Technology, Haifa Israel, 4 Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
We have pioneered an innovative and low-cost printing technique, known as direct ink writing (DIW), for the fabrication of micro-periodic oxide structures in both planar and 3D forms.* Using DIW, functional 1D arrays of TiO2 micro-wires and 3D micro-periodic structures have been patterned from concentrated sol-gel inks with characteristic feature sizes that range from ~200 nm (1D sensor arrays) to ~500 nm for 3D photonic crystals. DIW of well-defined 1D arrays of TiO2 microwires offers precise control of filament diameter and spatial location, enabling a systematic study of microwire TiO2 gas sensors. We show that TiO2 microwire arrays serve as highly sensitive gas sensors. To further demonstrate the versatility of the DIW printing approach, 3D micro-periodic structures composed of orthogonally-stacked layers of parallel oxide rods have been produced in a woodpile architecture. These 3D structures exhibit a partial photonic bandgap with a reflectivity of up to 92% in the near IR and a broad stop-peak width of ~26%. * E. B. Duoss, M. Twardowski, and J. A. Lewis, Adv. Mater. 19 (21), 3485 (2007).
3:15 PM - F5.3
Electroactive NanoInks and Printable NanoArchitectures for Energy-Efficient Thin Film Electronics.
Cheng Huang 1 , Peter Rieke 1 , Silas Towne 1 , Jim Holbery 1 , Howard Katz 2 Show Abstract
1 Chemical, Materials, and Electrical Engineering, Energy & Environment Directorate, Battelle, Pacific Northwest National Laboratory, Richland, Washington, United States, 2 Materials Science and Engineering, and Chemistry Department, Whiting School of Engineering, Johns Hopkins University, Baltimore, Maryland, United States
We are carrying out our work on Printed Thin Film Energy (PTFE) based on our competencies of printed thin film electronics, soft solution processing sciences, interface and surface sciences, thin films and smart coating technology. This develops new electroactive nanoinks and chemical printing techniques for rapid, efficient, inexpensive and continuous disposition and architectures of thin films and multilayer assemblies for use in printable electronics, especially for energy harvesting, storage, and conversion devices. Chemical printing offers the potential for rapid multilayer spatially resolved deposition of electroactive nanoinks and printable nanoarchitectures. It also has enhanced performance, higher utilization of inks, rapid and efficient deposition compatible with large area productions. We report the fabrication processes from transistor circuits, solar cells, and fuel cells, which result in high performance, reduced materials costs and reduced fabrication costs. This work was supported by NSF-ECS and DOE.
3:30 PM - F5.4
Nano Imprint Lithography on Silica Sol-gels: a Simple Route to Sequential Patterning.
Christophe Peroz 1 , Vanessa Chauveau 1 , Etienne Barthel 1 , Elin Sondergard 1 Show Abstract
1 Surface du Verre et Interfaces, CNRS/Saint-Gobain, Aubervilliers France
3:45 PM - F5.5
The Patterning of Sub-500 nm Inorganic Oxide and Nanocrystalline Semiconductor Structures.
Meredith Hampton 1 , Stuart Williams 1 , Zhilian Zhou 4 , Janine Nunes 1 , Doo-Hyun Ko 1 , Scott Retterer 2 , Joseph Templeton 1 , Edward Samulski 1 , Joseph DeSimone 1 3 Show Abstract
1 Chemistry, University of North Carolina, Chapel Hill, North Carolina, United States, 4 , Liquidia Technologies, Research Triangle Park, North Carolina, United States, 2 Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 3 Chemical Engineering, North Carolina State University, Raleigh, North Carolina, United States
The Pattern Replication In Non-wetting Templates (PRINT1) technique has been extended to patterning of isolated features as well as embossed films of sub-500 nm “hard” inorganic oxides and nanocrystalline semiconductors including TiO2, SnO2, ZnO, ITO, BaTiO3, and CdSe. The low surface energy, chemically resistant, air permeable, elastomeric perflouropolyether (PFPE) based molds allow for numerous materials to be patterned on a variety of substrates including glass and transparent conductive oxides for a wide range of electronic and optical applications. PRINT is a unique route that provides for (1) large area arrays of isolated features with uniformity and precise control over shape and size (2) the patterning of materials with large aspect ratios (3) layer by layer deposition without destruction of the first layer and (4) the patterning of an extensive array of materials with amenability to surface functionalization and (5) a cost effective fabrication process that is scalable for roll-to-roll manufacturing processes. We will additionally discuss pattern replication on the sub-100 nm scale for photovoltaic applications using line gratings fabricated with electron beam lithography.1. Rolland et al. J. Am. Chem. Soc. 2005, 127, 10096-10100.
4:30 PM - **F5.6
Advances in Materials for Printed Transistors.
Beng Ong 1 Show Abstract
1 , Institute of Materials Research and Engineering, Singapore Singapore
Printing thin-film transistors require solution processable conductor, semiconductor, and dielectric materials, which can be printed and retain their required performance characteristics after printing. This lecture reviews the design principles and critical issues for the development of these materials, particularly for high-throughput processing to enable low-cost transistor arrays/circuits. Progress towards design of high-performance semiconductor, conductor, and gate dielectric for this emerging technology will be presented.
5:15 PM - F5.8
Inkjet Printed Narrow Electrodes for High Performance Organic Thin-Film Transistors.
Jason Doggart 1 2 , Yiliang Wu 2 , Shiping Zhu 1 Show Abstract
1 Chemical Engineering, McMaster University, Burlington, Ontario, Canada, 2 New Materials Design Lab, Xerox Research Center of Canada, Mississauga, Ontario, Canada
Drop on demand inkjet printing has recently generated a great deal of interest as a fabrication method for printed organic electronic devices such as RFID tags and organic thin film transistors (OTFTs). Specifically, a great deal of research has investigated the use of this technique for high resolution printing of the conductive components of these devices. One of the greatest challenges to achieving this goal is the ability to print electrodes of uniform film thickness, which requires the elimination of the so called ‘coffee ring effect’. This effect describes the propensity of solute to accumulate at the periphery of a drying droplet, a result which can severely diminish the conductivity of printed electrodes. Some groups have suggested that a solution to this dilemma is the addition of a cosolvent which would induce a Marangoni flow to recirculate solvent back to the center. However this solution is only viable when a cosolvent of higher boiling point and lower surface tension than the major solvent is available. Here, we describe a more widely applicable method for eliminating the coffee ring effect which allows us to print highly resolute electrodes with excellent film thickness uniformity. Our study investigated the effect of both line width (controlled via dot-to-dot spacing during printing) and the concentration of a high boiling point cosolvent. It was found that by simultaneously optimizing these two variables, one could essentially eliminate the coffee ring effect and print electrodes of nearly uniform thickness. Furthermore, by increasing the viscosity of this ink (via silver concentration), the resolution was greatly improved, such that source and drain electrodes with both electrode width and channel lengths of less than 50μm could be obtained. Incorporation of these electrodes into OTFT devices using PQT – 12 as a semiconductor yielded high performance devices with mobility of 0.1 cm2V-1s-1 and an on/off current ratio of 107, indicating negligible additional contact resistance was introduced by the printed electrodes.
5:30 PM - F5.9
Ultrasonic Spray Assisted Mist-CVD Method for High-quality Crystalline and Amorphous Oxide Semiconductors Growth.
Hiroyuki Nishinaka 1 , Yudai Kamada 1 , Keiji Kiba 1 , Naoki Kameyama 1 , Shizuo Fujita 1 Show Abstract
1 Department of Electronic Science and Engineering, Kyoto University, Kyoto, Kyoto, Japan
Evolution of an inexpensive, safe and environmental-friendly ultrasonic spray assisted mist-chemical vapor deposition (CVD) method is definitely shown with the growth of high-quality crystalline and amorphous oxide semiconductors. In the mist-CVD, we use liquid solutions of source materials as precursors. They are ultrasonically atomized and the mist particles formed are transferred to the reaction area with the carrier gas[1,2]. In this way, the mist sources can substitute for vaporized sources of toxic and/or dangerous metalorganics, and therefore the mist-CVD can possess excellent controllability for source supply even comparable to metalorganic-CVD (MOCVD).An example to be shown and discussed is for the growth of ZnO and related materials. Using Zn(Ac)2 as a precursor for Zn with changing the substrate materials and temperatures, the following results have ever been obtained;(i)transparent and smooth c-axis oriented ZnO thin films were grown on glass substrates, (ii)ZnO films were grown at the temperature lower than 200C, (iii)ZnO nanowires were formed using Au catalyst, (iv)single-crystalline ZnO on sapphire attained the mobility of 70 cm2/Vs, which was reasonably high compared to various ZnO thin films grown by MOCVD, and (v)two-dimensional step-flow growth, which had been difficult by MOCVD, was achieved by homoepitaxial layers on ZnO substrates. Doping and alloy layers were successfully achieved by adding the required source precursors in the source solution. The results showed as followed; (i)Al-doped ZnO on glass attained low resistivity of 6x10-4Ωcm, which was a standard for certain applications as a transparent conducting oxide, and (ii)single crystalline (0001)-oriented wurtzite Zn1-xMgxO thin films on sapphire were prepared between x=0 and 0.25 without phase segregation of rocksalt structure.Other oxide thin films such as Al2O3 and Ga2O3 were also obtained by the mist-CVD method. The mixture of Ga2O3 and Al2O3, that is, (AlxGa1-x)2O3 successfully changed the optical bandgap. It may open new application by the growth of metastable α-Ga2O3, in contrast to strong tendency of growing β-Ga2O3, on sapphire (α-Al2O3), where the crystal structure matches between the epilayer and the substrate.Mist-CVD is a low cost solution-based growth method, but it can be compatible or even superior to MOCVD as evidenced by the growth of high quality ZnO single crystal thin films. This technique is also suitable for the growth of polycrystalline and amorphous films on large substrates for the fabrication of transparent thin films and thin film devices. In the symposium the advantages and potential of the mist-CVD method, which is not only low cost and environmental friendly but also superior to the existing CVD methods for the growth of oxide thin films are demonstrated and discussed.H. Nishinaka, T. Kawaharamura, S. Fujita, Jpn. J. Appl. Phys., 46 (2007) 6811. T. Kawaharamura, H. Nishinaka, S. Fujita, Jpn. J. Appl. Phys., 47 (2008) 4669.
F6: Poster Session: Porous, Sol-Gel and TCO
Thursday AM, December 04, 2008
Exhibition Hall D (Hynes)
9:00 PM - F6.1
Formation of Mesoporous Silica/Nanostructured Metal Thin Films by Dipcoating and Electrodeposition.
Roger Campbell 1 , Jason Manning 1 2 , Caleb Hill 2 , Martin Bakker 1 2 , Dong Ryeol Lee 3 , Xuefa Li 3 , Jin Wang 3 Show Abstract
1 Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama, United States, 2 Center for Materials for Information Technology, The University of Alabama, Tuscaloosa, Alabama, United States, 3 Advanced Photon Source, Argonne National Labortory, Argonne, Illinois, United States
The simple sol-gel synthesis of mesoporous silica thin films of a variety of geometries coupled with electrodeposition into the films has raised interest in the potential of such hybrid silica/metal nanostructures for applications in catalysis, information and energy storage, and sensors. Electrodeposition into mesoporous silica films has been largely limited to films formed on Indium Tin Oxide conducting glass. We have determined that both SBA-15 and SBA-16 mesoporous silica films can adhere to a range of metals, even after removal of the templating block copolymer. Electrodeposition of nickel and cobalt into the thin films has been clearly demonstrated in the case of the SBA-15, through the use of Grazing Incidence Small Angle X-ray Scattering (GISAXS) and magnetometry. However, TEM imaging suggests that the nanostructures grown into SBA-15 and SBA-16 are not stable for long periods of time.
9:00 PM - F6.10
Stabilizing Mesoporous Silica Films Using Multiple Organosilanes and Manipulating The Functionalization Sequence.
B. Singh 1 , A. Jain 1 , D. Gandhi 1 , R. Moore 2 , G. Ramanath 1 Show Abstract
1 Department of Materials Science & Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States, 2 College of Nanoscale Science & Engineering, State University of New York, Albany, New York, United States
Mesoporous silica (MPS) thin films are attractive candidates for electrically isolating adjacent layers in nanodevice wiring. While porosity decreases the signal propagation delays due to decreased resistance-capacitance coupling, the entailing high surface area makes MPS susceptible to moisture uptake and metal. Here, we show that passivating MPS with more than one organosilane with different molecular termini provides several-fold greater protection against such instabilities, than improvements observed by functionalizing MPS with either type of organosilane individually. We further show that the organosilane functionalization sequence is crucial, and can be used to fine tune the MPS film properties. Our findings are germane for realizing high-stability low k dielectrics for high-performance, high reliability nanodevices. Bias thermal annealing (BTA) measurements of Cu/treated-MPS/Si/Al structures with MPS films functionalized with bis[3-(triethoxysilyl)propyl] tetrasulfide (BTPTS) and trimethylchlorosilane (TMCS) exhibit at least 3 orders of magnitude greater time to dielectric breakdown compared to MPS functionalized individually with either organosilane. Infrared spectroscopy measurements indicate that the increased stability is due to Cu blocking by the multiple sulfur atoms in the tetrasulfide group in BTPTS and decreased moisture uptake is caused by hydrophobic passivation with TMCS. Reversing the functionalization sequence results in lower-k value, lower leakage currents and higher dielectric breakdown voltage. BTA and infrared spectroscopy measurements indicate that this difference is caused by more effective moisture removal in the latter case when MPS is treated with TMCS first. Furthermore, this sequence does not adversely impact Cu immobilization even though X-ray photoelectron and auger electron spectroscopy depth profiles indicate a lower sulfur content in films treated with TMCS first. This strategy can be conceivably extended to other functionalization chemistries for designing high stability porous low-k materials.
9:00 PM - F6.11