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Articles 2971 - 3000 of 3535

Full-Text Articles in Nanoscience and Nanotechnology

Electrocatalytic Oxidation Of Glucose On Cnt/Nanocrystlline Tio2-Pt Complex Film Electrode In Ionic Liquids, Dao-Bao Chu, Long-Wu Zha, Shu-Xi Wang, Jian Wang, Ying Xiao, Yuan-Yuan Hou, Jian-Guo He, Xue-Jiao Zhang Aug 2009

Electrocatalytic Oxidation Of Glucose On Cnt/Nanocrystlline Tio2-Pt Complex Film Electrode In Ionic Liquids, Dao-Bao Chu, Long-Wu Zha, Shu-Xi Wang, Jian Wang, Ying Xiao, Yuan-Yuan Hou, Jian-Guo He, Xue-Jiao Zhang

Journal of Electrochemistry

Using ionic liquid [EMI]BF4 as the electrolyte,the electrocatalytic oxidation of glucose on carbon nanotubes/nanocrystlline TiO2 film loaded on Pt (CNT/nanoTiO2-Pt) complex film electrode was investigated by cyclic voltammetry. The results found that the CNT/nanoTiO2-Pt complex electrode had high catalytic activity to the electrochemical oxidation of glucose in ionic liquids and the oxidation potential was -0.46 V. The best effect of glucose oxidation was obtained with the volume ratio of ionic liquid to water being 3:1. The process of electrodic reaction process was concentration polarization controlled.

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Self-Supporting Nanowire Arrays Templated In Sacrificial Branched Porous Anodic Alumina For Thermoelectric Devices, Kalapi G. Biswas, Hatem El Matbouly, Vijay Rawat, Jeremy L. Schroeder, Timothy D. Sands Aug 2009

Self-Supporting Nanowire Arrays Templated In Sacrificial Branched Porous Anodic Alumina For Thermoelectric Devices, Kalapi G. Biswas, Hatem El Matbouly, Vijay Rawat, Jeremy L. Schroeder, Timothy D. Sands

Birck and NCN Publications

Templated synthesis of thermoelectric nanowires in porous anodic alumina (PAA) have potential for enhanced performance relative to bulk materials. A significant challenge is the template material, which can serve as a thermal shunt. In this work, an approach for creating a branched PAA template is described. The process utilizes localized self-heating to destabilize the planar anodization front, yielding branched and interconnected pores growing at a rate of 300 mu m/h. The template is selectively etched after electrodeposition of desired materials, yielding self-supporting nanowire arrays with thicknesses up to about 300 mu m, thereby eliminating the thermal shunt through the template.

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Thermionic Emission Energy Distribution From Nanocrystalline Diamond Films For Direct Thermal-Electrical Energy Conversion Applications, Kishore Uppireddi, Tyler Westover, Timothy Fisher, Brad H. Weiner, Gerardo Morell Aug 2009

Thermionic Emission Energy Distribution From Nanocrystalline Diamond Films For Direct Thermal-Electrical Energy Conversion Applications, Kishore Uppireddi, Tyler Westover, Timothy Fisher, Brad H. Weiner, Gerardo Morell

Birck and NCN Publications

In the ongoing quest for energy production by nonconventional methods, energy conversion by vacuum and solid-state thermionic emission devices is one of the potentially efficient pathways for converting thermal energy directly into electrical power. The realization of practical of thermionic energy conversion devices strongly depends on achieving low work function materials, which is thus far a limiting factor. In an attempt to develop a new low work function thermionic material, this work reports thermionic emission energy distributions (TEEDs) from nanocrystalline diamond (NCD) films in the temperature range from 700 to 900 degrees C that reveal a consistent effective work function …

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Stable And Reproducible Electronic Conduction Through Dna Molecular Junctions, Ajit K. Mahapatro, Gil Lee, Kyung J. Jeong, David B. Janes Aug 2009

Stable And Reproducible Electronic Conduction Through Dna Molecular Junctions, Ajit K. Mahapatro, Gil Lee, Kyung J. Jeong, David B. Janes

Birck and NCN Publications

This letter presents the observation of stable and reproducible electronic conduction through double stranded (ds) DNA molecules in a nominally dry state. Stable conduction was realized by immobilizing 15 base-pair guanine:cytosine rich dsDNA within gold nanogap junctions, stabilizing the dsDNA with a polycation, and characterizing in nitrogen. In air, the current levels decrease with successive voltage scans likely due to oxidation of the guanine bases under bias. In nitrogen, reproducible current-voltage traces are observed and the current levels at specific bias points are stable with time. The stability allows comprehensive electrical studies and could enable conductance-based DNA sensors.

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Strain Relaxation In Si/Ge/Si Nanoscale Bars From Molecular Dynamics Simulations, Yumi Park, Hasan Metin Atkulga, Ananth Y. Grama, Alejandro Strachan Aug 2009

Strain Relaxation In Si/Ge/Si Nanoscale Bars From Molecular Dynamics Simulations, Yumi Park, Hasan Metin Atkulga, Ananth Y. Grama, Alejandro Strachan

Birck and NCN Publications

We use molecular dynamics (MD) with the reactive interatomic potential ReaxFF to characterize the local strains of epitaxial Si/Ge/Si nanoscale bars as a function of their width and height. While the longitudinal strain (along the bars length) is independent of geometry, surface relaxation leads to transverse strain relaxation in the Ge section. This strain relaxation increases with increasing height of the Ge section and reduction in its width and is complete (i.e., zero transverse strain) for roughly square cross sections of Ge leading to a uniaxial strain state. Such strain state is desirable in some microelectronics applications. From the MD …

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Strain Relaxation In Si/Ge/Si Nanoscale Bars From Molecular Dynamics Simulations, Yumi Park, Hasan Atkulga, Ananth Y. Grama, Alejandro Strachan Aug 2009

Strain Relaxation In Si/Ge/Si Nanoscale Bars From Molecular Dynamics Simulations, Yumi Park, Hasan Atkulga, Ananth Y. Grama, Alejandro Strachan

Birck and NCN Publications

We use molecular dynamics (MD) with the reactive interatomic potential ReaxFF to characterize the local strains of epitaxial Si/Ge/Si nanoscale bars as a function of their width and height. While the longitudinal strain (along the bars length) is independent of geometry, surface relaxation leads to transverse strain relaxation in the Ge section. This strain relaxation increases with increasing height of the Ge section and reduction in its width and is complete (i.e., zero transverse strain) for roughly square cross sections of Ge leading to a uniaxial strain state. Such strain state is desirable in some microelectronics applications. From the MD …

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Self-Supporting Nanowire Arrays Templated In Sacrificial Branched Porous Anodic Alumina For Thermoelectric Devices, Kalapi G. Biswas, Hatem El Matbouly, Vijay Rawat, Jeremy L. Schroeder, Timothy D. Sands Aug 2009

Self-Supporting Nanowire Arrays Templated In Sacrificial Branched Porous Anodic Alumina For Thermoelectric Devices, Kalapi G. Biswas, Hatem El Matbouly, Vijay Rawat, Jeremy L. Schroeder, Timothy D. Sands

Birck and NCN Publications

Templated synthesis of thermoelectric nanowires in porous anodic alumina (PAA) have potential for enhanced performance relative to bulk materials. A significant challenge is the template material, which can serve as a thermal shunt. In this work, an approach for creating a branched PAA template is described. The process utilizes localized self-heating to destabilize the planar anodization front, yielding branched and interconnected pores growing at a rate of 300 mu m/h. The template is selectively etched after electrodeposition of desired materials, yielding self-supporting nanowire arrays with thicknesses up to about 300 mu m, thereby eliminating the thermal shunt through the template.

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Thermionic Emission Energy Distribution From Nanocrystalline Diamond Films For Direct Thermal-Electrical Energy Conversion Applications, Kishore Uppireddi, Tyler Westover, Timothy Fisher, Brad Weiner, Gerardo Morell Aug 2009

Thermionic Emission Energy Distribution From Nanocrystalline Diamond Films For Direct Thermal-Electrical Energy Conversion Applications, Kishore Uppireddi, Tyler Westover, Timothy Fisher, Brad Weiner, Gerardo Morell

Birck and NCN Publications

In the ongoing quest for energy production by nonconventional methods, energy conversion by vacuum and solid-state thermionic emission devices is one of the potentially efficient pathways for converting thermal energy directly into electrical power. The realization of practical of thermionic energy conversion devices strongly depends on achieving low work function materials, which is thus far a limiting factor. In an attempt to develop a new low work function thermionic material, this work reports thermionic emission energy distributions (TEEDs) from nanocrystalline diamond (NCD) films in the temperature range from 700 to 900 °C that reveal a consistent effective work function of …

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Modeling Of Subcontinuum Thermal Transport Across Semiconductor-Gas Interfaces, Dhruv Singh, Xiaohui Guo, Alina Alexeenko, Jayathi Y. Murthy, Timothy S. Fisher Jul 2009

Modeling Of Subcontinuum Thermal Transport Across Semiconductor-Gas Interfaces, Dhruv Singh, Xiaohui Guo, Alina Alexeenko, Jayathi Y. Murthy, Timothy S. Fisher

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

A physically rigorous computational algorithm is developed and applied to calculate subcontinuum thermal transport in structures containing semiconductor-gas interfaces. The solution is based on a finite volume discretization of the Boltzmann equation for gas molecules in the gas phase and phonons in the semiconductor. A partial equilibrium is assumed between gas molecules and phonons at the interface of the two media, and the degree of this equilibrium is determined by the accommodation coefficients of gas molecules and phonons on either side of the interface. Energy balance is imposed to obtain a value of the interface temperature. The classic problem of …

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Non-Gray Phonon Transport Using A Hybrid Bte-Fourier Solver, James Loy, Druv Singh, Jayathi Y. Murthy Jul 2009

Non-Gray Phonon Transport Using A Hybrid Bte-Fourier Solver, James Loy, Druv Singh, Jayathi Y. Murthy

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

Non-gray phonon transport solvers based on the Boltzmann transport equation (BTE) are frequently employed to simulate sub-micron thermal transport. Typical solution procedures using sequential solution schemes encounter numerical difficulties because of the large spread in scattering rates. For frequency bands with very low Knudsen numbers, strong coupling between the directional BTEs results in slow convergence for sequential solution procedures. In this paper, we present a hybrid BTE-Fourier model which addresses this issue. By establishing a phonon group cutoff (say Kn=0.1), phonon bands with low Knudsen numbers are solved using a modified Fourier equation which includes a scattering term as well …

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Modeling Of Subcontinuum Thermal Transport Across Semiconductor-Gas Interfaces, Druv Singh, Xiaohui Guo, Alina Alexeenko, Jayathi Y. Murthy, Timothy Fisher Jul 2009

Modeling Of Subcontinuum Thermal Transport Across Semiconductor-Gas Interfaces, Druv Singh, Xiaohui Guo, Alina Alexeenko, Jayathi Y. Murthy, Timothy Fisher

Birck and NCN Publications

A physically rigorous computational algorithm is developed and applied to calculate subcontinuum thermal transport in structures containing semiconductor-gas interfaces. The solution is based on a finite volume discretization of the Boltzmann equation for gas molecules (in the gas phase) and phonons (in the semiconductor). A partial equilibrium is assumed between gas molecules and phonons at the interface of the two media, and the degree of this equilibrium is determined by the accommodation coefficients of gas molecules and phonons on either side of the interface. Energy balance is imposed to obtain a value of the interface temperature. The classic problem of …

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Squeeze-Film Damping Of Flexible Microcantilevers At Low Ambient Pressures: Theory And Experiment, Jin Lee, Ryan C. Tung, Arvind Raman, Hartono Sumali, John Sullivan Jul 2009

Squeeze-Film Damping Of Flexible Microcantilevers At Low Ambient Pressures: Theory And Experiment, Jin Lee, Ryan C. Tung, Arvind Raman, Hartono Sumali, John Sullivan

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

An improved theoretical approach is proposed to predict the dynamic behavior of long, slender and flexible microcantilevers affected by squeeze-film damping at low ambient pressures. Our approach extends recent continuum gas damping models (Veijola 2004 J. Micromech. Microeng. 14 1109–18, Gallis and Torczynski 2004 J. Microelectromech. Syst. 13 653–9), which were originally derived for a rigid oscillating plate near a wall, to flexible microcantilevers for calculating and predicting squeeze-film damping ratios of higher order bending modes at reduced ambient pressures. Theoretical frequency response functions are derived for a flexible microcantilever beam excited both inertially and via external forcing. Experiments performed …

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Tunable Magnetic Response Of Metamaterials, Shumin Xiao, Uday K. Chettiar, Alexander V. Kildishev, V. Drachev, I C. Khoo, V. M. Shalaev Jul 2009

Tunable Magnetic Response Of Metamaterials, Shumin Xiao, Uday K. Chettiar, Alexander V. Kildishev, V. Drachev, I C. Khoo, V. M. Shalaev

Birck and NCN Publications

We demonstrate a thermally tunable optical metamaterial with negative permeability working in the visible range. By covering coupled metallic nanostrips with aligned nematic liquid crystals (NLCs), the magnetic response wavelength of the metamaterial is effectively tuned through control of the ambient temperature, changing the refractive index of LC via phase transitions. By increasing the ambient temperature from 20 to 50 degrees C, the magnetic response wavelength shifts from 650 to 632 nm. Numerical simulations confirm our tests and match the experimental observations well.

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Translation Of Nanoantenna Hot Spots By A Metal-Dielectric Composite Superlens, Zhengtong Liu, Mark D. Thoreson, Alexander V. Kildishev, V. M. Shalaev Jul 2009

Translation Of Nanoantenna Hot Spots By A Metal-Dielectric Composite Superlens, Zhengtong Liu, Mark D. Thoreson, Alexander V. Kildishev, V. M. Shalaev

Birck and NCN Publications

We employ numerical simulations to show that highly localized, enhanced electromagnetic fields, also known as "hot spots," produced by a periodic array of silver nanoantennas can be spatially translated to the other side of a metal-dielectric composite superlens. The proposed translation of the hot spots enables surface-enhanced optical spectroscopy without the undesirable contact of molecules with metal, and thus it broadens and reinforces the potential applications of sensing based on field-enhanced fluorescence and surface-enhanced Raman scattering.

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Translation Of Nanoantenna Hot Spots By A Metal-Dielectric Composite Superlens, Zhengtong Liu, Mark D. Thoreson, Alexander V. Kildishev, V. M. Shalaev Jul 2009

Translation Of Nanoantenna Hot Spots By A Metal-Dielectric Composite Superlens, Zhengtong Liu, Mark D. Thoreson, Alexander V. Kildishev, V. M. Shalaev

Birck and NCN Publications

We employ numerical simulations to show that highly localized, enhanced electromagnetic fields, also known as "hot spots," produced by a periodic array of silver nanoantennas can be spatially translated to the other side of a metal-dielectric composite superlens. The proposed translation of the hot spots enables surface-enhanced optical spectroscopy without the undesirable contact of molecules with metal, and thus it broadens and reinforces the potential applications of sensing based on field-enhanced fluorescence and surface-enhanced Raman scattering.

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Vertical Carbon Nanotube Devices With Nanoscale Lengths Controlled Without Lithography, Aaron D. Franklin, Robert A. Sayer, Timothy D. Sands, David B. Janes, Timothy S. Fisher Jul 2009

Vertical Carbon Nanotube Devices With Nanoscale Lengths Controlled Without Lithography, Aaron D. Franklin, Robert A. Sayer, Timothy D. Sands, David B. Janes, Timothy S. Fisher

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

Vertical single-walled carbon nanotubes (vSWCNTs) are synthesized within highly ordered porous anodic alumina (PAA) templates supported on Si substrates. A process for obtaining thin-film PAA with long-range ordered nanopores is presented in this paper. Each nanopore contains at most one v-SWCNT that is supported by a dielectric and addressed by electrochemically formed Pd nanowire source contacts and evaporated Pd drain contacts. Characteristics of these completely vertical, two-terminal nanotube devices are presented. Control of the v-SWCNT length is demonstrated using a straightforward etching process with lengths of less than 100 nm achieved without the need for complex/expensive lithography. This effective nanoscale …

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Simplified Model For Periodic Nanoantennae: Linear Model And Inverse Design, Joshua Borneman, Kuo-Ping Chen, Alexander V. Kildishev, V. M. Shalaev Jul 2009

Simplified Model For Periodic Nanoantennae: Linear Model And Inverse Design, Joshua Borneman, Kuo-Ping Chen, Alexander V. Kildishev, V. M. Shalaev

Birck and NCN Publications

We determine and use a minimal set of numerical simulations to create a simplified model for the spectral response of nanoantennae with respect to their geometric and modeling parameters. The simplified model is then used to rapidly obtain best-fit modeling parameters to match experimental results, accurately predict the spectral response for various geometries, and inversely design antennae to have a desired performance. This method is structure and model independent, and is applied here to both nanoantenna pair arrays and strips modeled using a 3D finite-element method and 2D spatial harmonic analysis, respectively. Typical numerical simulations may need hours per model, …

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Ultrasensitive Protein Detection In Blood Serum Using Gold Nanoparticle Probes By Single Molecule Spectroscopy, Jiji Chen, Chungang Wang, Joseph Irudayaraj Jul 2009

Ultrasensitive Protein Detection In Blood Serum Using Gold Nanoparticle Probes By Single Molecule Spectroscopy, Jiji Chen, Chungang Wang, Joseph Irudayaraj

Birck and NCN Publications

A one-step rapid and ultrasensitive immunoassay capable of detecting proteins in blood serum is developed using gold nanoprobes and fluorescence correlation spectroscopy (FCS). In this approach we take advantage of the inherent photoluminescence property of gold nanoparticles (GNPs) to develop a fluorophore-free assay to observe binding entities by monitoring the diffusion of bound versus unbound molecules in a limited confocal volume. 40-nm GNPs conjugated separately with rabbit anti-IgG (Fc) and goat anti-IgG (Fab) when incubated in blood serum containing IgG forms a sandwich structure constituting dimers and oligomers that can be differentiated by to detect IgG in blood serum at …

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Pseudomorphic Stabilization Of Rocksalt Gan In Tin/Gan Multilayers And Superlattices, Vijay Rawat, Dmitri Zakharov, E A. Stach, Timothy D. Sands Jul 2009

Pseudomorphic Stabilization Of Rocksalt Gan In Tin/Gan Multilayers And Superlattices, Vijay Rawat, Dmitri Zakharov, E A. Stach, Timothy D. Sands

Birck and NCN Publications

Gallium nitride (GaN) in its stable wurtzite phase has proven its utility in light-emitting diodes and diode lasers as well as high-temperature and high-power electronic devices. In addition to its equilibrium wurtzite phase, GaN exhibits two cubic polymorphs, a zinc-blende phase and a high-pressure rocksalt phase. Here, we report the pseudomorphic stabilization of the high-pressure rocksalt phase of GaN within TiN/GaN multilayers as verified using x-ray diffraction and high-resolution transmission electron microscopy. High-resolution lattice imaging confirmed that the lattice parameter of the rocksalt GaN phase is 0.41 nm. The critical thickness of the GaN film that can be pseudomophically stabilized …

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Metamaterial Devices For The Terahertz Band, Gabriel Paul Kniffin Jun 2009

Metamaterial Devices For The Terahertz Band, Gabriel Paul Kniffin

Center for Electron Microscopy and Nanofabrication Publications and Presentations

Terahertz (THz) and metamaterials are both hot topics in electromagnetics research. The THz band (0.1-10 THz) lies in the ‘gap’ between microwave and far infrared regions. Research is currently underway to characterize how these waves interact with matter, with potential applications including security screening, medical imaging, and non-destructive evaluation. Metamaterials are artificial materials containing sub-wavelength structures whose material properties, μ and ǫ can be ‘tuned’ to desired specifications, including simultaneously negative values, resulting in exotic properties such as a negative refractive index. Current metamaterials research includes the design of devices that operate at THz frequencies, filling a niche left wide …

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Flexible Electronics Using Ion Implantation To Adhere Polymer Substrate To Single Crystal Silicon Substrate, Terry L. Alford, Douglas C. Thompson Jr., Hyunchul Kim, Michael A. Nastasi, James W. Mayer, Daniel Adams Jun 2009

Flexible Electronics Using Ion Implantation To Adhere Polymer Substrate To Single Crystal Silicon Substrate, Terry L. Alford, Douglas C. Thompson Jr., Hyunchul Kim, Michael A. Nastasi, James W. Mayer, Daniel Adams

Department of Mechanical and Materials Engineering: Faculty Publications

An electronic apparatus uses a single crystalline silicon Substrate disposed adjacent to a flexible substrate. The electronic apparatus may be a flexible flat panel display, or a flexible printed circuit board. The flexible substrate can be made from polymer, plastic, paper, flexible glass, and stainless steel. The flexible substrate is bonded to the single crystalline substrate using an ion implantation process. The ion implantation process involves the use of a noble gas Such as hydrogen, helium, Xenon, and krypton. A plurality of semiconductor devices are formed on the single crystalline silicon Substrate. The semi conductor devices may be thin film …

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Temperature Dependence Of Hot-Carrier Relaxation In Pbse Nanocrystals: An Ab Initio Study, Hua Bao, Bradley F. Habenicht, Oleg V. Prezhdo, X Ruan Jun 2009

Temperature Dependence Of Hot-Carrier Relaxation In Pbse Nanocrystals: An Ab Initio Study, Hua Bao, Bradley F. Habenicht, Oleg V. Prezhdo, X Ruan

Birck and NCN Publications

Temperature-dependent dynamics of phonon-assisted relaxation of hot carriers, both electrons and holes, is studied in a PbSe nanocrystal using ab initio time-domain density-functional theory. The electronic structure is first calculated, showing that the hole states are denser than the electron states. Fourier transforms of the time-resolved energy levels show that the hot carriers couple to both acoustic and optical phonons. At higher temperature, more phonon modes in the high-frequency range participate in the relaxation process due to their increased occupation number. The phonon-assisted hot-carrier relaxation time is predicted using nonadiabatic molecular dynamics, and the results clearly show a temperature-activation behavior. …

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Thermal Conductivity Of Bismuth Telluride Nanowire Array-Epoxy Composite, Kalapi G. Biswas, Timothy D. Sands, Baratunde Cola, Xianfan Xu Jun 2009

Thermal Conductivity Of Bismuth Telluride Nanowire Array-Epoxy Composite, Kalapi G. Biswas, Timothy D. Sands, Baratunde Cola, Xianfan Xu

Birck and NCN Publications

Electrodeposition of nanowire array in porous anodic alumina (PAA) templates combine the performance benefits offered by crystallographic texture control, lattice thermal conductivity suppression through boundary scattering of phonons, elastic relaxation of misfit strain, and scalablity essential for high efficiency thermoelectric devices. The template material, however, can serve as a thermal shunt thereby reducing the effective thermoelectric performance. Here, we demonstrate a process of minimizing the parasitic thermal conduction by replacing the PAA matrix with SU-8 (kappa similar to 0.2 W/m K). We report a reduction in the performance penalty from 27% for Bi2Te3/PAA to similar to 5% for Bi2Te3/SU-8 nanocomposite …

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Demonstration Of Quadrature-Squeezed Surface Plasmons In A Gold Waveguide, Alexander Huck, Stephan Smolka, Peter Lodahl, Anders S. Sorensen, Alexandra Boltasseva, Jiri Janousek, Ulrik Andersen Jun 2009

Demonstration Of Quadrature-Squeezed Surface Plasmons In A Gold Waveguide, Alexander Huck, Stephan Smolka, Peter Lodahl, Anders S. Sorensen, Alexandra Boltasseva, Jiri Janousek, Ulrik Andersen

Birck and NCN Publications

We report on the efficient generation, propagation, and reemission of squeezed long-range surface-plasmon polaritons in a gold waveguide. Squeezed light is used to excite the nonclassical surface-plasmon polaritons, and the reemitted quantum state is fully characterized by complete quantum tomographic reconstruction of the density matrix. We find that the plasmon-assisted transmission of nonclassical light in metallic waveguides can be described by a beam splitter relation. This result is explained theoretically.

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Performance Analysis Of Statistical Samples Of Graphene Nanoribbon Tunneling Transistors With Line Edge Roughness, Mathieu Luisier, Gerhard Klimeck Jun 2009

Performance Analysis Of Statistical Samples Of Graphene Nanoribbon Tunneling Transistors With Line Edge Roughness, Mathieu Luisier, Gerhard Klimeck

Birck and NCN Publications

Using a three-dimensional, atomistic quantum transport simulator based on the tight-binding method, we investigate statistical samples of single-gate graphene nanoribbon (GNR) tunneling field-effect transistors (TFETs) with different line edge roughness probabilities. We find that as the nanoribbon edges become rougher, the device OFF-current drastically increases due to a reduction of the graphene band gap and an enhancement of source-to-drain tunneling leakage through the gate potential barrier. At the same time, the ON-current remains almost constant. This leads to a deterioration of the transistor subthreshold slopes and to unacceptably low ON/OFF current ratios limiting the switching performances of GNR TFETs.

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Demonstration Of Quadrature-Squeezed Surface Plasmons In A Gold Waveguide, Alexander Huck, Stephan Smolka, Peter Lodahl, Anders S. Sorensen, Alexandra Boltasseva, Jiri Janousek, Ulrik Andersen Jun 2009

Demonstration Of Quadrature-Squeezed Surface Plasmons In A Gold Waveguide, Alexander Huck, Stephan Smolka, Peter Lodahl, Anders S. Sorensen, Alexandra Boltasseva, Jiri Janousek, Ulrik Andersen

Birck and NCN Publications

We report on the efficient generation, propagation, and reemission of squeezed long-range surface-plasmon polaritons in a gold waveguide. Squeezed light is used to excite the nonclassical surface-plasmon polaritons, and the reemitted quantum state is fully characterized by complete quantum tomographic reconstruction of the density matrix. We find that the plasmon-assisted transmission of nonclassical light in metallic waveguides can be described by a beam splitter relation. This result is explained theoretically.

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Anisotropic Metamaterials Emulated By Tapered Waveguides: Application To Optical Cloaking, Igor I. Smolyaninov, Vera N. Smolyaninova, Alexander V. Kildishev, V. M. Shalaev May 2009

Anisotropic Metamaterials Emulated By Tapered Waveguides: Application To Optical Cloaking, Igor I. Smolyaninov, Vera N. Smolyaninova, Alexander V. Kildishev, V. M. Shalaev

Birck and NCN Publications

We demonstrate that metamaterial devices requiring anisotropic dielectric permittivity and magnetic permeability may be emulated by specially designed tapered waveguides. This approach leads to low-loss, broadband performance. Based on this technique, we demonstrate broadband electromagnetic cloaking in the visible frequency range on a scale similar to 100 times larger than the wavelength.

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Influence Of Nano-Al2O3 Particles In Nickel Electro-Crystallization Process, Cheng-Yu Tan, Wei Hu, Hang Cui, Yu Liu May 2009

Influence Of Nano-Al2O3 Particles In Nickel Electro-Crystallization Process, Cheng-Yu Tan, Wei Hu, Hang Cui, Yu Liu

Journal of Electrochemistry

The influence of nano-Al2O3 particles in nickel electro-deposition on copper matrix from acid sulphate solution was studied under various potentials by using cyclic voltammetry(CV) and chronoamperometry(CA).The results show that the beginning potential of electro-deposition was about-740 mV(vs.SCE) for Ni-Al2O3 solution system.With the step-potential moving to the negative direction,the nucleation time of electro-deposition for Ni-Al2O3 solution system was shortened gradually.Compared with that of pure Ni deposition system,the nucleation time tm,corresponding to the peak current of Ni-Al2O3 deposition system was apparently shortened under the lower step-potential:-740~-830 mV,which indicates that Al …

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Metal-Oxide-Semiconductor Field-Effect Transistors On Gaas (111)A Surface With Atomic-Layer-Deposited Al2o3 As Gate Dielectrics, Xu M, Y Q. Wu, O Koybasi, T Shen, P. D. Ye May 2009

Metal-Oxide-Semiconductor Field-Effect Transistors On Gaas (111)A Surface With Atomic-Layer-Deposited Al2o3 As Gate Dielectrics, Xu M, Y Q. Wu, O Koybasi, T Shen, P. D. Ye

Birck and NCN Publications

GaAs inversion-mode metal-oxide-semiconductor field-effect transistors (MOSFETs) with atomic-layer-deposited Al2O3 as gate dielectrics are fabricated on (111)A and (100) surfaces. With the same channel length of 0.75 mu m, the maximum drain current of 15 mA/mm on n-channel MOSFET is obtained on (111)A surface, in great contrast to only 1 mu A/mm on (100) surface. For p-channel MOSFETs, maximum drain currents of 0.17 mA/mm and 0.8 mA/mm are obtained on (111)A and (100) surfaces, respectively. An empirical model is proposed to correlate the experimental observation with the existing III-V MOS theories.

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Device Considerations For Development Of Conductance-Based Biosensors, Kangho Lee, Pradeep R. Nair, Adina Scott, Muhammad A. Alam, David B. Janes May 2009

Device Considerations For Development Of Conductance-Based Biosensors, Kangho Lee, Pradeep R. Nair, Adina Scott, Muhammad A. Alam, David B. Janes

Birck and NCN Publications

Design and fabrication of electronic biosensors based on field-effect-transistor (FET) devices require understanding of interactions between semiconductor surfaces and organic biomolecules. From this perspective, we review practical considerations for electronic biosensors with emphasis on molecular passivation effects on FET device characteristics upon immobilization of organic molecules and an electrostatic model for FET-based biosensors.

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