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Articles 4261 - 4290 of 6327

Full-Text Articles in Engineering

Distributed Negf Algorithms For The Simulation Of Nanoelectronic Devices With Scattering, Stephen Cauley, Mathieu Luisier, Venkataramanan Balakrishnan, Gerhard Klimeck, Cheng-Kok Koh Mar 2011

Distributed Negf Algorithms For The Simulation Of Nanoelectronic Devices With Scattering, Stephen Cauley, Mathieu Luisier, Venkataramanan Balakrishnan, Gerhard Klimeck, Cheng-Kok Koh

Birck and NCN Publications

Through the Non-Equilibrium Green’s Function (NEGF) formalism, quantum- scale device simulation can be performed with the inclusion of electron-phonon scattering. However, the simulation of realistically sized devices under the NEGF formalism typically requires prohibitive amounts of memory and computation time. Two of the most demanding computational problems for NEGF simulation involve mathematical operations with structured matrices called semiseparable matrices. In this work, we present parallel approaches for these computational problems which allow for efficient distribution of both memory and computation based upon the underlying device structure. This is critical when simulating realistically sized devices due to the aforementioned computational burdens. …

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Interfacial Effects On Droplet Dynamics In Poiseuille Flow, Kendra Erk, Jonathan T. Schwalbe, Frederick R. Phelan Jr., Petia M. Vlahovska, Steven D. Hudson Mar 2011

Interfacial Effects On Droplet Dynamics In Poiseuille Flow, Kendra Erk, Jonathan T. Schwalbe, Frederick R. Phelan Jr., Petia M. Vlahovska, Steven D. Hudson

School of Materials Engineering Faculty Publications

Many properties of emulsions arise from interfacial rheology, but a theoretical understanding of the effect of interfacial viscosities on droplet dynamics is lacking. Here we report such a theory, relating to isolated spherical drops in a Poiseuille flow. Stokes flow is assumed in the bulk phases, and a jump in hydrodynamic stress at the interface is balanced by Marangoni and surface viscous forces according to the Boussinesq–Scriven constitutive law. Our model employs a linear equation of state for the surfactant. Our analysis predicts slip, cross-stream migration and droplet-circulation velocities. These results and the corresponding interfacial parameters are separable: e.g., cross-stream …

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Subband Engineering For P-Type Silicon Ultra-Thin Layers For Increased Carrier Velocities: An Atomistic Analysis, Neophytos Neophytou, Gerhard Klimeck Mar 2011

Subband Engineering For P-Type Silicon Ultra-Thin Layers For Increased Carrier Velocities: An Atomistic Analysis, Neophytos Neophytou, Gerhard Klimeck

Birck and NCN Publications

Ultra-thin-body (UTB) channel materials of a few nanometers in thickness are currently considered as candidates for future electronic, thermoelectric, and optoelectronic applications. Among the features that they possess, which make them attractive for such applications, their confinement length scale, transport direction, and confining surface orientation serve as degrees of freedom for engineering their electronic properties. This work presents a comprehensive study of hole velocities in p-type UTB films of widths from 15 nm down to 3 nm. Various transport and surface orientations are considered. The atomistic sp3d5s*-spin-orbit-coupled tight-binding model is used for the electronic structure, and a semiclassical ballistic model …

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Subband Engineering For P-Type Silicon Ultra-Thin Layers For Increased Carrier Velocities: An Atomistic Analysis, Neophytos Neophytou, Gerhard Klimeck, Hans Kosina Mar 2011

Subband Engineering For P-Type Silicon Ultra-Thin Layers For Increased Carrier Velocities: An Atomistic Analysis, Neophytos Neophytou, Gerhard Klimeck, Hans Kosina

Other Nanotechnology Publications

Ultra-thin-body (UTB) channel materials of a few nanometers in thickness are currently considered as candidates for future electronic, thermoelectric, and optoelectronic applications. Among the features that they possess, which make them attractive for such applications, their confinement length scale, transport direction, and confining surface orientation serve as degrees of freedom for engineering their electronic properties. This work presents a comprehensive study of hole velocities in p-type UTB films of widths from 15 nm down to 3 nm. Various transport and surface orientations are considered. The atomistic sp3d5s*-spin-orbit-coupled tight-binding model is used for the electronic structure, and a semiclassical ballistic model …

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Atomistic Study Of Electronic Structure Of Pbse Nanowires, Abhijeet Paul, Gerhard Klimeck Mar 2011

Atomistic Study Of Electronic Structure Of Pbse Nanowires, Abhijeet Paul, Gerhard Klimeck

Birck and NCN Publications

Lead Selenide (PbSe) is an attractive ‘IV-VI’ semiconductor material to design optical sensors, lasers and thermoelectric devices. Improved fabrication of PbSe nanowires (NWs) enables the utilization of low dimensional quantum effects. The effect of cross-section size (W) and channel orientation on the bandstructure of PbSe NWs is studied using an 18 band sp3d5 tight-binding theory. The bandgap increases almost with the inverse of the W for all the orientations indicating a weak symmetry dependence. [111] and [110] NWs show higher ballistic conductance for the conduction and valence band compared to [100] NWs due to the significant splitting of the projected …

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Atomistic Study Of Electronic Structure Of Pbse Nanowires, Abhijeet Paul, Gerhard Klimeck Mar 2011

Atomistic Study Of Electronic Structure Of Pbse Nanowires, Abhijeet Paul, Gerhard Klimeck

Birck and NCN Publications

Lead Selenide (PbSe) is an attractive ‘IV-VI’ semiconductor material to design optical sensors, lasers and thermoelectric devices. Improved fabrication of PbSe nanowires (NWs) enables the utilization of low dimensional quantum effects. The effect of cross-section size (W) and channel orientation on the bandstructure of PbSe NWs is studied using an 18 band sp3d5 tight-binding theory. The bandgap increases almost with the inverse of the W for all the orientations indicating a weak symmetry dependence. [111] and [110] NWs show higher ballistic conductance for the conduction and valence band compared to [100] NWs due to the significant splitting of the projected …

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Polarity Effects In The X-Ray Photoemission Of Zno And Other Wurtzite Semiconductors, M. W. Allen, Dmitry Zemlyanov, G.I.N. Waterhouse, J. B. Metson, T. D. Veal, C. F. Mcconville, S. M. Durbin Mar 2011

Polarity Effects In The X-Ray Photoemission Of Zno And Other Wurtzite Semiconductors, M. W. Allen, Dmitry Zemlyanov, G.I.N. Waterhouse, J. B. Metson, T. D. Veal, C. F. Mcconville, S. M. Durbin

Birck and NCN Publications

Significant polarity-related effects were observed in the near-surface atomic composition and valence band electronic structure of ZnO single crystals, investigated by x-ray photoemission spectroscopy using both Al K(alpha) (1486.6 eV) and synchrotron radiation (150 to 1486 eV). In particular, photoemission from the lowest binding energy valence band states was found to be significantly more intense on the Zn-polar face compared to the O-polar face. This is a consistent effect that can be used as a simple, nondestructive indicator of crystallographic polarity in ZnO and other wurtzite semiconductors. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3562308]

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Coherent Electron Transport By Adiabatic Passage In An Imperfect Donor Chain, Rajib Rahman, Richard P. Muller, James E. Levy, Malcolm S. Carroll, Gerhard Klimeck, Andrew D. Greentree, Lloyd C. L. Hollenberg Mar 2011

Coherent Electron Transport By Adiabatic Passage In An Imperfect Donor Chain, Rajib Rahman, Richard P. Muller, James E. Levy, Malcolm S. Carroll, Gerhard Klimeck, Andrew D. Greentree, Lloyd C. L. Hollenberg

Birck and NCN Publications

Coherent tunneling adiabatic passage 􏰀CTAP􏰁 has been proposed as a long-range physical quantum bits 􏰀qubit􏰁 transport mechanism in solid-state quantum computing architectures. Although the mechanism can be implemented in either a chain of quantum dots or donors, a one-dimensional chain of donors in Si is of particular interest due to the natural confining potential of donors that can, in principle, help reduce the gate densities in solid-state quantum computing architectures. Using detailed atomistic modeling, we investigate CTAP in a more realistic triple donor system in the presence of inevitable fabrication imperfections. In particular, we investigate how an adiabatic pathway for …

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Effects Of Gate-Last And Gate-First Process On Deep Submicron Inversion-Mode Ingaas N-Channel Metal-Oxide-Semiconductor Field Effect Transistors, J. J. Gu, Y. Q. Wu, Peide D. Ye Mar 2011

Effects Of Gate-Last And Gate-First Process On Deep Submicron Inversion-Mode Ingaas N-Channel Metal-Oxide-Semiconductor Field Effect Transistors, J. J. Gu, Y. Q. Wu, Peide D. Ye

Birck and NCN Publications

Recently, encouraging progress has been made on surface-channel inversion-mode In-rich InGaAs NMOSFETs with superior drive current, high transconductance and minuscule gate leakage, using atomic layer deposited (ALD) high-k dielectrics. Although gate-last process is favorable for high-k/III-V integration, high-speed logic devices require a self-aligned gate-first process for reducing the parasitic resistance and overlap capacitance. On the other hand, a gate-first process usually requires higher thermal budget and may degrade the III-V device performance. In this paper, we systematically investigate the thermal budget of gate-last and gate-first process for deep-submicron InGaAs MOSFETs. We conclude that the thermal instability of (NH(4))(2)S as the …

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Chemical Response Of Lithiated Graphite With Deuterium Irradiation, C. N. Taylor, B. Heim, Jean Paul Allain Mar 2011

Chemical Response Of Lithiated Graphite With Deuterium Irradiation, C. N. Taylor, B. Heim, Jean Paul Allain

Birck and NCN Publications

Lithium wall conditioning has been found to enhance plasma performance for graphite walled fusion devices such as TFTR, CDX-U, T-11M, TJ-II and NSTX. Among observed plasma enhancements is a reduction in edge density and reduced deuterium recycling. The mechanism by which lithiated graphite retains deuterium is largely unknown. Under controlled laboratory conditions, X-ray photoelectron spectroscopy (XPS) is used to observe the chemical changes that occur on ATJ graphite after lithium deposition. The chemical state of lithiated graphite is found to change upon deuterium irradiation indicating the formation Li-O-D, manifest at 532.9 +/- 0.6 eV. Lithium-deuterium interactions are also manifest in …

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2011 Directory Of Indiana State, County, City And Town Officials Responsible For Road And Street Work, Indiana Ltap Mar 2011

2011 Directory Of Indiana State, County, City And Town Officials Responsible For Road And Street Work, Indiana Ltap

Indiana Local Technical Assistance Program (LTAP) Directory

Contact information for local agency officials and employees responsible for Indiana’s local road infrastructure.

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Accurate Six-Band Nearest-Neighbor Tight-Binding Model For The Π-Bands Of Bulk Graphene And Graphene Nanoribbons, Timothy B. Boykin, Mathieu Luisier, Gerhard Klimeck, Xueping Jiang, Neerav Kharche, Yu Zhou, Saroj K. Nayak Mar 2011

Accurate Six-Band Nearest-Neighbor Tight-Binding Model For The Π-Bands Of Bulk Graphene And Graphene Nanoribbons, Timothy B. Boykin, Mathieu Luisier, Gerhard Klimeck, Xueping Jiang, Neerav Kharche, Yu Zhou, Saroj K. Nayak

Birck and NCN Publications

Accurate modeling of the ␣-bands of armchair graphene nanoribbons (AGNRs) requires correctly reproducing asymmetries in the bulk graphene bands as well as providing a realistic model for hydrogen passivation of the edge atoms. The commonly used single-pz orbital approach fails on both these counts. To overcome these failures we introduce a nearest-neighbor, three orbital per atom p/d tight-binding model for graphene. The parameters of the model are fit to first-principles density-functional theory (DFT) – based calculations as well as to those based on the many-body Green’s function and screened-exchange (GW) formalism, giving excellent agreement with the ab initio AGNR bands. …

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Surface-Enhanced Raman Imaging Of Intracellular Bioreduction Of Chromate In Shewanella Oneidensis, Sandeep P. Ravindranath, Kristene Henne, Dorothea Thompson, Joseph Irudayaraj Feb 2011

Surface-Enhanced Raman Imaging Of Intracellular Bioreduction Of Chromate In Shewanella Oneidensis, Sandeep P. Ravindranath, Kristene Henne, Dorothea Thompson, Joseph Irudayaraj

Birck and NCN Publications

This proposed research aims to use novel nanoparticle sensors and spectroscopic tools constituting surface-enhanced Raman spectroscopy (SERS) and Fluorescence Lifetime imaging (FLIM) to study intracellular chemical activities within single bioremediating microorganism. The grand challenge is to develop a mechanistic understanding of chromate reduction and localization by the remediating bacterium Shewanella oneidensis MR-1 by chemical and lifetime imaging. MR-1 has attracted wide interest from the research community because of its potential in reducing multiple chemical and metallic electron acceptors. While several biomolecular approaches to decode microbial reduction mechanisms exist, there is a considerable gap in the availability of sensor platforms to …

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Tuning Lattice Thermal Conductance By Porosity Control In Ultrascaled Si And Ge Nanowires, Abhijeet Paul, Gerhard Klimeck Feb 2011

Tuning Lattice Thermal Conductance By Porosity Control In Ultrascaled Si And Ge Nanowires, Abhijeet Paul, Gerhard Klimeck

Birck and NCN Publications

Porous nanowires 􏰎NWs􏰍 with tunable thermal conductance are examined as a candidate for thermoelectric devices with high efficiency. Thermal conductance 􏰎􏱆l􏰍 of porous NWs is calculated using the phonon dispersion obtained from a modified valence force field model. Porosity in the NWs break the crystal symmetry leading to the reduction in ballistic 􏱆l. 􏰐100􏰑 Si and Ge NWs show similar percentage reductions in 􏱆l for the same amount of porosity. The model predicts an anisotropic reduction in 􏱆l in SiNWs, with 􏰐111􏰑 showing the maximum reduction followed by 􏰐100􏰑 and 􏰐110􏰑 for a similar hole radius. The reduction in 􏱆l …

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The Composite Materials Manufacturaing Hub - Crowd Sourcing As The Norm, R. Byron Pipes, Gerhard Klimeck, Mark R. Pipes Feb 2011

The Composite Materials Manufacturaing Hub - Crowd Sourcing As The Norm, R. Byron Pipes, Gerhard Klimeck, Mark R. Pipes

Birck and NCN Publications

The Composites Manufacturing HUB puts compo- sites manufacturing simulations in the hands of those who need them to invent new and innovative ways to capture the extraordinary benefits of these high perfor- mance products at an acceptable manufactured cost. The HUB provides the user simple browser access to power- ful tools that simulate the actual steps and outcome con- ditions of a complex manufacturing process without the need to download and maintain software in the conven- tional manner. Learning use of the manufacturing simu- lation tools will also be accomplished on the HUB in or- der to allow for continuous …

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Interface Trap Density Metrology From Sub-Threshold Transport In Highly Scaled Undoped Si N-Finfets, Abhijeet Paul, Giuseppe C. Tettamanz, Sunhee Lee, Saumitra R. Mehrotra, Nadine Collaert, Serge Biesemans, Sven Rogge, Gerhard Klimeck Feb 2011

Interface Trap Density Metrology From Sub-Threshold Transport In Highly Scaled Undoped Si N-Finfets, Abhijeet Paul, Giuseppe C. Tettamanz, Sunhee Lee, Saumitra R. Mehrotra, Nadine Collaert, Serge Biesemans, Sven Rogge, Gerhard Klimeck

Birck and NCN Publications

Channel conductance measurements can be used as a tool to study thermally activated electron transport in the sub-threshold region of state-of-art FinFETs. Together with theoretical Tight- Binding (TB) calculations, this technique can be used to understand the evolution of source-to- channel barrier height (Eb) and of active channel area (S) with gate bias (Vgs). The quantitative difference between experimental and theoretical values that we observe can be attributed to the interface traps present in these FinFETs. Therefore, based on the difference between measured and calculated values of (i) S and (ii) |∂Eb/∂Vgs| (channel to gate coupling), two new methods of …

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Understanding The Impact Of Indot Projects On Automotive Industry Cluster Logistics Costs: A Case Study Of The Honda Plant, Ananth Iyer, Barry K. Partridge, Mary Pilotte, Pete Mast, Gerald Simms Feb 2011

Understanding The Impact Of Indot Projects On Automotive Industry Cluster Logistics Costs: A Case Study Of The Honda Plant, Ananth Iyer, Barry K. Partridge, Mary Pilotte, Pete Mast, Gerald Simms

JTRP Technical Reports

No abstract provided.

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2009 Summary Of Highway Revenues, Distributions, & Expenses For Indiana Counties, Cities, & Towns, Indiana Ltap Feb 2011

2009 Summary Of Highway Revenues, Distributions, & Expenses For Indiana Counties, Cities, & Towns, Indiana Ltap

Indiana Local Technical Assistance Program (LTAP) Publications

This report provides information on revenues, distributions, and expenses of state and local governments for highway, road, and street work. Since the Motor Vehicle Highway (MVH) and Local Road and Street (LRS) Accounts are the principal source of funds for local road or street construction and maintenance operations, this summary may be used to see the trends in income sources and in the expenses charged to the funds prior to their being distributed to the highway, road, and street agencies.

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Molecular Dynamics Characterization Of The Contact Between Clean Metallic Surfaces With Nanoscale Asperities, Hojin Kim, Alejandro Strachan Jan 2011

Molecular Dynamics Characterization Of The Contact Between Clean Metallic Surfaces With Nanoscale Asperities, Hojin Kim, Alejandro Strachan

Birck and NCN Publications

We use molecular dynamics (MD) simulations to characterize the tensile strength of contacts formed between various clean platinum surfaces with nanoscale asperities. Both commensurate contacts between (001) and (111) surfaces and incommensurate (001) ones are considered over a wide range of asperity sizes. In cyclic closing and opening, fresh asperities that form contacts for the first time show significant plastic deformation; this leads to a reduction in the effective contact area during the first few cycles, after which steady state is achieved both in terms of contact size and the pull-out force necessary to open the contacts. As is the …

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Estimating The Yield Strength Of Thin Metal Films Through Elastic-Plastic Buckling-Induced Debonding, S Goyal, K Srinivasan, G Subbarayan, Thomas Siegmund Jan 2011

Estimating The Yield Strength Of Thin Metal Films Through Elastic-Plastic Buckling-Induced Debonding, S Goyal, K Srinivasan, G Subbarayan, Thomas Siegmund

School of Mechanical Engineering Faculty Publications

In this paper, we propose a procedure to estimate the yield strength of thin films by debonding films from their substrate by elastic-plastic buckling under thermally-induced compressive loading. The out-of-plane displacement of the metal lines under conditions of elastic-plastic buckling is dependent on the yield strength of the film. Thus, an inverse estimate of the yield strength is made from measurements of the out-of-plane displacements of the buckled metal lines. The procedure is demonstrated to estimate the yield strength of aluminum lines consistent with measurements by other techniques.

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Lattice Thermal Conductivity Reduction In Bi2te3 Quantum Wires With Smooth And Rough Surfaces: A Molecular Dynamics Study, Bo Qiu, Lin Sun, Xiulin Ruan Jan 2011

Lattice Thermal Conductivity Reduction In Bi2te3 Quantum Wires With Smooth And Rough Surfaces: A Molecular Dynamics Study, Bo Qiu, Lin Sun, Xiulin Ruan

Birck and NCN Publications

Using molecular dynamics simulations, we have predicted the thermal conductivity of Bi2Te3 nanowires with diameters ranging from 3 to 30 nm with both smooth and rough surfaces. It is found that when the nanowire diameter decreases to the molecular scale (below 10 nm, or the so-called "quantum wire"), the thermal conductivity shows significant reduction as compared to bulk value. On the other hand, the thermal conductivity for the 30-nm-diam nanowire only shows less than 20% reduction, in agreement with recent experimental data. Also, the thermal conductivity of nanowires shows a weaker temperature dependence than the typical T-1 trend, consistent with …

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Phonon-Limited And Effective Low-Field Mobility In N- And P-Type [100]-, [110]-, And [111]-Oriented Si Nanowire Transistors, Mathieu Luisier Jan 2011

Phonon-Limited And Effective Low-Field Mobility In N- And P-Type [100]-, [110]-, And [111]-Oriented Si Nanowire Transistors, Mathieu Luisier

Birck and NCN Publications

Ultrascaled n- and p-type Si nanowire field-effect transistors (NW FETs) with [100], [110], and [111] as channel orientations are simulated in the presence of electron-phonon scattering using an atomistic quantum transport solver based on the sp(3)d(5)s* tight-binding model for electrons and holes, a modified Keating model for phonons, and the nonequilibrium Green's function formalism. The channel resistances of devices with different gate lengths and carrier concentrations are computed at room temperature and used to extract phonon-limited, ballistic, and effective low-field mobilities. It is found that a [110] channel represents the best choice for high n- and p-type NW FET performances. …

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Effect Of Strain On Stripe Phases In The Quantum Hall Regime, Sunanda P. Koduvayur, Yuli Lyanda-Geller, Sergei Khlebnikov, Gabor Csathy, Michael J. Manfra, Loren N. Pfeiffer, Kenneth W. West, Leonid P. Rokhinson Jan 2011

Effect Of Strain On Stripe Phases In The Quantum Hall Regime, Sunanda P. Koduvayur, Yuli Lyanda-Geller, Sergei Khlebnikov, Gabor Csathy, Michael J. Manfra, Loren N. Pfeiffer, Kenneth W. West, Leonid P. Rokhinson

Birck and NCN Publications

Preferential orientation of the stripe phases in the quantum Hall (QH) regime has remained a puzzle since its discovery. We show experimentally and theoretically that the direction of high and low resistance of the two-dimensional (2D) hole gas in the QH regime can be controlled by an external strain. Depending on the sign of the in-plane shear strain, the Hartree-Fock energy of holes or electrons is minimized when the charge density wave (CDW) is oriented along the [110] or [1 (1) over bar0] directions. We suggest that shear strains due to internal electric fields in the growth direction are responsible …

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Influence Of Cross-Section Geometry And Wire Orientation On The Phonon Shifts In Ultra-Scaled Si Nanowires, Abhijeet Paul, Mathieu Luisier, Gerhard Klimeck Jan 2011

Influence Of Cross-Section Geometry And Wire Orientation On The Phonon Shifts In Ultra-Scaled Si Nanowires, Abhijeet Paul, Mathieu Luisier, Gerhard Klimeck

Birck and NCN Publications

Engineering of the cross-section shape and size of ultra-scaled Si nanowires (SiNWs) provides an attractive way for tuning their structural properties. The acoustic and optical phonon shifts of the free-standing circular, hexagonal, square and triangular SiNWs are calculated using a Modified Valence Force Field (MVFF) model. The acoustic phonon blue shift (acoustic hardening) and the optical phonon red shift (optical softening) show a strong dependence on the cross-section shape and size of the SiNWs. The triangular SiNWs have the least structural symmetry as revealed by the splitting of the degenerate flexural phonon modes and The show the minimum acoustic hardening …

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Identification And Analysis Of Common Bean (Phaseolus Vulgaris L.) Transcriptomes By Massively Parallel Pyrosequencing, Venu Kalavacharla, Zhanji Liu, Blake C. Meyers, Jyothi Thimmapuram, Kalpalatha Melmaiee Jan 2011

Identification And Analysis Of Common Bean (Phaseolus Vulgaris L.) Transcriptomes By Massively Parallel Pyrosequencing, Venu Kalavacharla, Zhanji Liu, Blake C. Meyers, Jyothi Thimmapuram, Kalpalatha Melmaiee

Cyber Center Publications

Common bean (Phaseolus vulgaris) is the most important food legume in the world. Although this crop is very important to both the developed and developing world as a means of dietary protein supply, resources available in common bean are limited. Global transcriptome analysis is important to better understand gene expression, genetic variation, and gene structure annotation in addition to other important features. However, the number and description of common bean sequences are very limited, which greatly inhibits genome and transcriptome research. Here we used 454 pyrosequencing to obtain a substantial transcriptome dataset for common bean.

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A Compact Physical Model For Morphology Induced Intrinsic Degradation Of Polymer Based Bulk Heterojunction Solar Cell, Biswajit Ray, Muhammad A. Alam Jan 2011

A Compact Physical Model For Morphology Induced Intrinsic Degradation Of Polymer Based Bulk Heterojunction Solar Cell, Biswajit Ray, Muhammad A. Alam

Birck and NCN Publications

The gradual loss of efficiency during field operation poses a fundamental challenge for economic viability of any solar cell technology. Well known examples include light-induced degradation in Si-based cell (Staebler-Wronski effect), Cu diffusion in thin film (CIGS) cell, hot-spot degradation in series connected modules, etc. Here we develop a compact model for an intrinsic degradation concern for bulk heterojunction type organic photovoltaic (BH-OPV) cells that involve continued (thermal) phase segregation of the donor-acceptor molecules leading to characteristic loss of efficiency and performance. Our approach interprets a number of BH-OPV device degradation measurements within a common framework and suggests/rationalizes intuitive routes …

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Privacy-Preserving Assessment Of Location Data Trustworthiness, Chenyun Dai, Fang-Yu Rao, Gabriel Ghinita, Elisa Bertino Jan 2011

Privacy-Preserving Assessment Of Location Data Trustworthiness, Chenyun Dai, Fang-Yu Rao, Gabriel Ghinita, Elisa Bertino

Cyber Center Publications

Assessing the trustworthiness of location data corresponding to individuals is essential in several applications, such as forensic science and epidemic control. To obtain accurate and trustworthy location data, analysts must often gather and correlate information from several independent sources, e.g., physical observation, witness testimony, surveillance footage, etc. However, such information may be fraudulent, its accuracy may be low, and its vol-
ume may be insufficient to ensure highly trustworthy data. On the other hand, recent advancements in mobile computing and positioning systems, e.g., GPS-enabled cell phones, highway sensors, etc., bring new and effective technological means to track the location of …

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Effects Of Interface Roughness Scattering On Radio Frequency Performance Of Silicon Nanowire Transistors, Sunggeun Kim, Mathieu Luisier, Timothy B. Boykin, Gerhard Klimeck Jan 2011

Effects Of Interface Roughness Scattering On Radio Frequency Performance Of Silicon Nanowire Transistors, Sunggeun Kim, Mathieu Luisier, Timothy B. Boykin, Gerhard Klimeck

Birck and NCN Publications

The effects of an atomistic interface roughness in n-type silicon nanowire transistors (SiNWT) on the radio frequency performance are analyzed. Interface roughness scattering (IRS) is statistically investigated through a three dimensional full–band quantum transport simulation based on the sp3d5s∗ tight–binding model. As the diameter of the SiNWT is scaled down below 3 nm, IRS causes a significant reduction of the cut-off frequency. The fluctuations of the conduction band edge due to the rough surface lead to a reflection of electrons through mode-mismatch. This effect reduces the velocity of electrons and hence the transconductance considerably causing a cut-off frequency reduction.

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Effects Of Interface Disorder On Valley Splitting In Sige/Si/Sige Quantum Wells, Zhengping Jiang, Neerav Kharche, Timothy Boykin, Gerhard Klimeck Jan 2011

Effects Of Interface Disorder On Valley Splitting In Sige/Si/Sige Quantum Wells, Zhengping Jiang, Neerav Kharche, Timothy Boykin, Gerhard Klimeck

Birck and NCN Publications

A sharp potential barrier at the Si/SiGe interface introduces valley splitting (VS), which lifts the 2-fold valley degeneracy in strained SiGe/Si/SiGe quantum wells (QWs). This work examines in detail the effects of Si/SiGe interface disorder on the VS in an atomistic tight binding approach based on statistical sampling. VS is analyzed as a function of electric field, QW thickness, and simulation domain size. Strong electric fields push the electron wavefunctions into the SiGe buffer and introduce significant VS fluctuations from device to device. A Gedankenexperiment with ordered alloys sheds light on the importance of different bonding configurations on VS. We …

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Shape And Orientation Effects On The Ballistic Phonon Thermal Properties Of Ultra-Scaled Si Nanowires, Abhijeet Paul, Mathieu Luisier, Gerhard Klimeck Jan 2011

Shape And Orientation Effects On The Ballistic Phonon Thermal Properties Of Ultra-Scaled Si Nanowires, Abhijeet Paul, Mathieu Luisier, Gerhard Klimeck

Birck and NCN Publications

The effect of geometrical confinement, atomic position and orientation of Silicon nanowires (SiNWs) on their thermal properties are investigated using the phonon dispersion obtained using a Modified Valence Force Field (MVFF) model. The spe- cific heat (Cv) and the ballistic thermal conductance (κbal) shows anisotropic variation l with changing cross-section shape and size of the SiNWs. The Cv increases with de- creasing cross-section size for all the wires. The triangular wires show the largest Cv due to their highest surface-to-volume ratio. The square wires with [110] orientation show the maximum κbal since they have the highest number of conducting phonon …

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