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2010

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Articles 1 - 30 of 94

Full-Text Articles in Nanoscience and Nanotechnology

Universality Of Non-Ohmic Shunt Leakage In Thin-Film Solar Cells, Sourabh Dongaonkar, J. D. Servaites, G. M. Ford, S. Loser, R. M. Gelfand, H. Mohseni, Hugh Hillhouse, R. Agrawal, M. A. Ratner, T. J. Marks, Mark S. Lundstrom, Muhammad A. Alam Dec 2010

Universality Of Non-Ohmic Shunt Leakage In Thin-Film Solar Cells, Sourabh Dongaonkar, J. D. Servaites, G. M. Ford, S. Loser, R. M. Gelfand, H. Mohseni, Hugh Hillhouse, R. Agrawal, M. A. Ratner, T. J. Marks, Mark S. Lundstrom, Muhammad A. Alam

Other Nanotechnology Publications

We compare the dark current-voltage (IV) characteristics of three different thin-film solar cell types: hydrogenated amorphous silicon (a-Si:H) p-i-n cells, organic bulk heterojunction (BHJ) cells, and Cu(In, Ga)Se-2 (CIGS) cells. All three device types exhibit a significant shunt leakage current at low forward bias (V < similar to 0.4) and reverse bias, which cannot be explained by the classical solar cell diode model. This parasitic shunt current exhibits non-Ohmic behavior, as opposed to the traditional constant shunt resistance model for photovoltaics. We show here that this shunt leakage (I-sh), across all three solar cell types considered, is characterized by the following common phenomenological features: (a) voltage symmetry about V = 0, (b) nonlinear (power law) voltage dependence, and (c) extremely weak temperature dependence. Based on this analysis, we provide a simple method of subtracting this shunt current component from the measured data and discuss its implications on dark IV parameter extraction. We propose a space charge limited (SCL) current model for capturing all these features of the shunt leakage in a consistent framework and discuss possible physical origin of the parasitic paths responsible for this shunt current mechanism. (C) 2010 American Institute of Physics. [doi:10.1063/1.3518509]


Uncertainty Propagation In A Multiscale Model Of Nanocrystalline Plasticity, Marisol Koslowski, Alejandro Strachan Dec 2010

Uncertainty Propagation In A Multiscale Model Of Nanocrystalline Plasticity, Marisol Koslowski, Alejandro Strachan

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

We characterize how uncertainties propagate across spatial and temporal scales in a physicsbased model of nanocrystalline plasticity of fcc metals. Our model combines molecular dynamics (MD) simulations to characterize atomic level processes that govern dislocation basedplastic deformation with a phase field approach to dislocation dynamics (PFDD) that describes how an ensemble of dislocations evolve and interact to determine the mechanical response of the material. We apply this approach to a nanocrystalline Ni specimen of interest in micro-electromechanical (MEMS) switches. Our approach enables us to quantify how internal stresses that result from the fabrication process affect the properties of dislocations (using ...


Generalized Ellipsometry On Sculptured Thin Films Made By Glancing Angle Deposition, Daniel Schmidt Dec 2010

Generalized Ellipsometry On Sculptured Thin Films Made By Glancing Angle Deposition, Daniel Schmidt

Theses, Dissertations, and Student Research from Electrical & Computer Engineering

In this thesis, physical properties of highly optically and magnetically anisotropic metal sculptured thin films made by glancing angle deposition are presented. Predominantly, the determination of optical and magneto-optical properties with spectroscopic generalized Mueller matrix ellipsometry and homogenization approaches is discussed. Nomenclatures are proposed to unambiguously identify the sculptured thin film geometry.

Generalized ellipsometry, a non-destructive optical characterization technique, is employed to determine geometrical structure and anisotropic dielectric properties of highly spatially coherent three-dimensionally nanostructured thin films in the spectral range from 400 to 1700 nm. The analysis of metal slanted columnar thin films (F1-STFs) deposited at glancing angle (θ ...


Small-Scale Solutions To Grand Challenges In Thermal Management, Suresh V. Garimella Nov 2010

Small-Scale Solutions To Grand Challenges In Thermal Management, Suresh V. Garimella

Birck and NCN Publications

Research needs in the field of thermal management of microelectronics and microsystems are identified, followed by a brief discussion of recent advances in solution approaches. These include novel solutions that rely on two-phase flow at the microscale, micropumps, droplet actuation on structured surfaces, passive transport in wick structures, ion-driven and piezoelectrically driven airflow, nanostructured thermal materials, and novel diagnostic tools.


Synthesis Of Mild–Hard Aao Templates For Studying Magnetic Interactions Between Metal Nanowires, Jin-Hee Lim, Aurelian Rotaru, Seong-Gi Min, Leszek Malkinski, John B. Wiley Nov 2010

Synthesis Of Mild–Hard Aao Templates For Studying Magnetic Interactions Between Metal Nanowires, Jin-Hee Lim, Aurelian Rotaru, Seong-Gi Min, Leszek Malkinski, John B. Wiley

Physics Faculty Publications

The sequential application of mild and hard anodization techniques in the fabrication of porous aluminamembranes allows one to decrease the number of continuous pores in anodized aluminium oxide (AAO) templates. Initially, standard mild anodization techniques were used to create porous templates with 100 nm interpore distances and 70 nm pore diameters. Hard anodization treatment on the same membrane then produced interpore distances of about 265 nm with diameters of 110 nm. At the interface between the two anodization steps, many of the mild-side pores were terminated to create a mild–hard membrane (Mi–Ha AAO) where the functional interpore distances ...


Determining The Electronic Properties Of Individual Nanointerfaces By Combining Intermittent Afm Imaging And Contact Spectroscopy, Ramsey A. Kraya, Dawn A. Bonnell Nov 2010

Determining The Electronic Properties Of Individual Nanointerfaces By Combining Intermittent Afm Imaging And Contact Spectroscopy, Ramsey A. Kraya, Dawn A. Bonnell

Departmental Papers (MSE)

A method to determine the electronic properties at nanointerfaces or of nanostructures by utilizing intermittent contact atomic force microscopy and contact spectroscopy in one system is developed. By combining these two methods, the integrity of the interface or structure is maintained during imaging, while the extraction of the electronic information is obtained with contact spectroscopy. This method is especially vital for understanding interfaces between metal nanoparticles and substrates, where the nanoparticles are not tethered to the surface and can be combined with new and evolving techniques of thermal drift compensation to allow for a larger range of experiments on nanointerfaces ...


Intracellular Localisation, Geno- And Cytotoxic Response Of Poly N-Isopropylacrylamide (Pnipam) Nanoparticles To Human Keratinocyte (Hacat) And Colon Cells (Sw 480), Pratap Naha, Kunal Bhattacharya, Tiziana Tenuta, Kenneth Dawson, Iseult Lynch, Amaya Gracia, Fiona Lyng, Hugh Byrne Oct 2010

Intracellular Localisation, Geno- And Cytotoxic Response Of Poly N-Isopropylacrylamide (Pnipam) Nanoparticles To Human Keratinocyte (Hacat) And Colon Cells (Sw 480), Pratap Naha, Kunal Bhattacharya, Tiziana Tenuta, Kenneth Dawson, Iseult Lynch, Amaya Gracia, Fiona Lyng, Hugh Byrne

Articles

PNIPAM nanoparticles, with and without a covalentlylinked fluorescent label, were prepared by a free radical polymerisation technique. The cyto and genotoxicity of PNIPAM nanoparticles were analysed in two representative mammalian cell lines, SW480, a colon, and HaCaT, a dermal cell line. Physical characterisation in terms of particle size and zeta potential of the PNIPAM nanoparticles was carried out both in aqueous solution and in the appropriate cell culture media. Uptake and colocalisation of fluorescently labelled PNIPAM nanoparticles was monitored in both cell lines using confocal laser scanning microscopy. Genotoxicity analysis using the Comet assay was performed in both cell lines ...


Atom Scale Characterization Of The Near Apex Region Of An Atomic Force Microscope Tip, Christopher J. Tourek, Sriram Sundararajan Oct 2010

Atom Scale Characterization Of The Near Apex Region Of An Atomic Force Microscope Tip, Christopher J. Tourek, Sriram Sundararajan

Mechanical Engineering Publications

Three-dimensional atom probe tomography (APT) is successfully used to analyze the near-apex regions of an atomic force microscope (AFM) tip. Atom scale material structure and chemistry from APT analysis for standard silicon AFM tips and silicon AFM tips coated with a thin film of Cu is presented. Comparison of the thin film data with that observed using transmission electron microscopy indicates that APT can be reliably used to investigate the material structure and chemistry of the apex of an AFM tip at near atomic scales.


Uncertainty Quantification Study For A Comprehensive Electrostatic Mems Switch Model, Michael G. Snow, Anil K. Bajaj Sep 2010

Uncertainty Quantification Study For A Comprehensive Electrostatic Mems Switch Model, Michael G. Snow, Anil K. Bajaj

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

This work presents an uncertainty analysis of a comprehensive model for an electrostatic MEMS switch. The goal is to elucidate the effects of parameter variations on certain performance characteristics. A sufficiently detailed model of an electrostatically actuated beam is developed. This model accounts for various physical effects, including the electrostatic fringing field, finite length of electrodes, squeeze film damping, and contact between the beam and the dielectric layer. The performance characteristics of immediate interest are the static and dynamic pull-in voltages for switch. Using Latin Hypercube and other sampling methods, the model is evaluated to find these performances characteristics when ...


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 Sep 2010

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 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 1D 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 CTAP is ...


Negative Dielectrophoretic Capture Of Bacterial Spores In Food Matrices, Mehti Koklu, Seungkyung Park, Suresh D. Pillai, Ali Beskok Sep 2010

Negative Dielectrophoretic Capture Of Bacterial Spores In Food Matrices, Mehti Koklu, Seungkyung Park, Suresh D. Pillai, Ali Beskok

Mechanical & Aerospace Engineering Faculty Publications

A microfluidic device with planar square electrodes is developed for capturing particles from high conductivity media using negative dielectrophoresis (n-DEP). Specifically, Bacillus subtilis and Clostridium sporogenes spores, and polystyrene particles are tested in NaCl solution (0.05 and 0.225 S/m), apple juice (0.225 S/m), and milk (0.525 S/m). Depending on the conductivity of the medium, the Joule heating produces electrothermal flow (ETF), which continuously circulates and transports the particles to the DEP capture sites. Combination of the ETF and n-DEP results in different particle capture efficiencies as a function of the conductivity. Utilizing 20 ...


Nanofibers And Nanoparticles From The Insect-Capturing Adhesive Of The Sundew (Drosera) For Cell Attachment, Mingjun Zhang, Scott C. Lenaghan, Lijin Xia, Lixin Dong, Wei He, William R. Henson, Xudong Fan Aug 2010

Nanofibers And Nanoparticles From The Insect-Capturing Adhesive Of The Sundew (Drosera) For Cell Attachment, Mingjun Zhang, Scott C. Lenaghan, Lijin Xia, Lixin Dong, Wei He, William R. Henson, Xudong Fan

Faculty Publications and Other Works -- Mechanical, Aerospace and Biomedical Engineering

Background

The search for naturally occurring nanocomposites with diverse properties for tissue engineering has been a major interest for biomaterial research. In this study, we investigated a nanofiber and nanoparticle based nanocomposite secreted from an insect-capturing plant, the Sundew, for cell attachment. The adhesive nanocomposite has demonstrated high biocompatibility and is ready to be used with minimal preparation.

Results

Atomic force microscopy (AFM) conducted on the adhesive from three species of Sundew found that a network of nanofibers and nanoparticles with various sizes existed independent of the coated surface. AFM and light microscopy confirmed that the pattern of nanofibers corresponded ...


Comprehensive Reduced-Order Models Of Electrostatically Actuated Mems Switches And Their Dynamics Including Impact And Bounce, Michael G. Snow, Anil K. Bajaj Aug 2010

Comprehensive Reduced-Order Models Of Electrostatically Actuated Mems Switches And Their Dynamics Including Impact And Bounce, Michael G. Snow, Anil K. Bajaj

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

As MEMS technology develops it is becoming better understood that MEMS designers must account for the large uncertainties characteristic of the relevant manufacturing processes. Uncertainty quantification tasks the designer with evaluating many different possible outcomes from the manufacturing process which creates a demand for models that are accurate and comprehensive, yet fast to evaluate. This work presents a comprehensive reduced-order model of electrostatically actuated switches incorporating a range of effects that are typically included only in FE modeling codes. Specifically, the model accounts for variable electrode geometry, stretching of centerline or large displacement effects, fringing field, squeeze film and rarefied ...


Simulation Of Sub-Micron Thermal Transport In A Mosfet Using A, James Loy, Druv Singh, Jayathi Y. Murthy Aug 2010

Simulation Of Sub-Micron Thermal Transport In A Mosfet Using A, James Loy, Druv Singh, Jayathi Y. Murthy

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

Self-heating has emerged as a critical bottleneck to scaling in modern transistors. In simulating heat conduction in these devices, it is important to account for the granularity of phonon transport since electron-phonon scattering occurs preferentially to select phonon groups. However, a complete accounting for phonon dispersion, polarization and scattering is very expensive if the Boltzmann transport equation (BTE) is used. Moreover, difficulties with convergence are encountered when the phonon Knudsen number becomes small. In this paper we simulate a two-dimensional bulk MOSFET hotspot problem using a partially-implicit hybrid BTE-Fourier solver which is significantly less expensive than a full BTE solution ...


Time Dependence Of Self-Assembly Process For The Formation Of Inorganic-Organic Hybrid Nanolayers, Alexandre Dhôtel Aug 2010

Time Dependence Of Self-Assembly Process For The Formation Of Inorganic-Organic Hybrid Nanolayers, Alexandre Dhôtel

Engineering Mechanics Dissertations & Theses

There is increasing interest in self-assembled materials for energy storage, flexible electronics and hydrophobic barriers. Inorganic/organic hybrid thin films and especially organosilane-based coatings already have demonstrated their ability to achieve those goals. However, some fundamental points of their formation process by molecular self-assembly remain unexplained. Although the literature widely reports the effect of temperature on the final nanostructure, until now, no one has taken into account the importance of time during their synthesis.

The main objective of this study was to improve and complete the understanding of mechanisms responsible for the self-organization of organic/inorganic molecules into a highly ...


High Aspect Ratio Nanoscale Metallic Structures As Transparent Electrodes, Ping Kuang, Joong Mok Park, Wai Y. Leung, Tae-Geun Kim, Kristen P. Constant Aug 2010

High Aspect Ratio Nanoscale Metallic Structures As Transparent Electrodes, Ping Kuang, Joong Mok Park, Wai Y. Leung, Tae-Geun Kim, Kristen P. Constant

Materials Science and Engineering Conference Papers, Posters and Presentations

A novel technique based on the two polymer micro-transfer molding (2-P μTM) for fabricating one dimensional (1D) high aspect ratio nanoscale metallic structures is presented and experimental characterization is described. Glancing angle metal deposition and physical argon ion milling (etching) techniques were also employed in processing. The resulting metallic structures have high transmission (~80%) in the visible spectrum and have superior electrical conductivity (resistance from 2.4 -7.3 Ω) compared to standard indium-tin oxide (ITO) glass. Thus, the high aspect ratio metallic structures are a promising alternative with potentially superior performances to ITO glass as transparent electrodes for organic ...


Acoustic Phonon Scattering In Bi2te3/Sb2te3 Superlattices, Yaguo Wang, Carl Liebig, Xianfan Xu, Rama Venkatasubramanian Aug 2010

Acoustic Phonon Scattering In Bi2te3/Sb2te3 Superlattices, Yaguo Wang, Carl Liebig, Xianfan Xu, Rama Venkatasubramanian

Birck and NCN Publications

Ultrafast time-resolved measurements were conducted to investigate long-wavelength acoustic phonon scattering and velocity reduction in Bi2Te3/Sb2Te3 superlattices. We show that both these phenomena suppress heat transfer process, with the phonon scattering contributing more in differentiating the lattice thermal conductivities among films with different periods. Measurements of reduction in the acoustic phonon amplitudes support the decrease in the thermal conductivity for certain superlattice periods, which is not predicted by acoustic mismatch theory. This study is a direct measurement of coherent acoustic phonons in superlattices which is of significant interest to thermoelectrics.


Iii-Nitride Nanopyramid Light Emitting Diodes Grown By Organometallic Vapor Phase Epitaxy, Isaac Wildeson, Robert Colby, David Ewoldt, Zhiwen Liang, Dmitri Zakharov, Nestor J. Zaluzec, R. Edwin García, E A. Stach, Timothy D. Sands Aug 2010

Iii-Nitride Nanopyramid Light Emitting Diodes Grown By Organometallic Vapor Phase Epitaxy, Isaac Wildeson, Robert Colby, David Ewoldt, Zhiwen Liang, Dmitri Zakharov, Nestor J. Zaluzec, R. Edwin García, E A. Stach, Timothy D. Sands

Birck and NCN Publications

Nanopyramid light emitting diodes (LEDs) have been synthesized by selective area organometallic vapor phase epitaxy. Self-organized porous anodic alumina is used to pattern the dielectric growth e templates via reactive ion etching, eliminating the need for lithographic processes. (In,Ga)N quantum well growth occurs primarily on the six {1 (1) over bar 01} semipolar facets of each of the nanopyramids, while coherent (In,Ga)N quantum dots with heights of up to similar to 20 nm are incorporated at the apex by controlling growth conditions. Transmission electron microscopy (TEM) indicates that the (In,Ga)N active regions of the ...


Metric Signature Transitions In Optical Metamaterials, Igor Smolyaninov, Evgenii Narimanov Aug 2010

Metric Signature Transitions In Optical Metamaterials, Igor Smolyaninov, Evgenii Narimanov

Birck and NCN Publications

We demonstrate that the extraordinary waves in indefinite metamaterials experience an (- - + +) effective metric signature. During a metric signature change transition in such a metamaterial, a Minkowski space-time is created together with a large number of particles populating the space-time. Such metamaterial models provide a tabletop realization of metric signature change events suggested to occur in Bose-Einstein condensates and quantum gravity theories.


Microcantilever Dynamics In Liquid Environment Dynamic Atomic Force Microscopy When Using Higher-Order Cantilever Eigenmodes, Daniel Kiracofe, Arvind Raman Aug 2010

Microcantilever Dynamics In Liquid Environment Dynamic Atomic Force Microscopy When Using Higher-Order Cantilever Eigenmodes, Daniel Kiracofe, Arvind Raman

Birck and NCN Publications

Dynamic atomic force microscopy is currently evolving from a single to a multifrequency instrument for nanoscale imaging often employing higher-order microcantilever eigenmodes for improved resolution and force spectroscopy. In this work the authors study the fundamentals of cantilever dynamics and energy dissipation when soft cantilevers are driven at their second flexural eigenmode and interact with samples in liquid environments. Contrary to the conventional first eigenmode operation, second eigenmode operation in liquids is often dominated by a subharmonic response (e.g., one tap every four drive cycles) and there is an energy transfer to the first eigenmode creating a new channel ...


Eight-Channel Reconfigurable Microring Filters With Tunable Frequency, Extinction Ratio And Bandwidth, Hao Shen, Maroof H. Khan, Li Fan, Lin Zhao, Yi Xuan, Jing Ouyang, Leo T. Varghese, Minghao Qi Aug 2010

Eight-Channel Reconfigurable Microring Filters With Tunable Frequency, Extinction Ratio And Bandwidth, Hao Shen, Maroof H. Khan, Li Fan, Lin Zhao, Yi Xuan, Jing Ouyang, Leo T. Varghese, Minghao Qi

Birck and NCN Publications

We demonstrate an eight-channel reconfigurable optical filter on a silicon chip. It consists of cascaded microring resonators and integrated compact heaters. With an embedded Mach-Zehnder (MZ) arm coupling to a microring resonator, the important parameters of a filter such as center frequency, extinction ratio and bandwidth can be controlled simultaneously for purposes of filtering, routing and spectral shaping. Thus our device could potentially be useful in dense wavelength division multiplexing (DWDM) and radio frequency arbitrary waveform generation (RFAWG). Multichannel filter response was successfully tuned to match the International Telecommunication Unit (ITU) grid with 50, 100 and 200GHz in channel spacing ...


Current Density And Continuity In Discretized Models, Timothy B. Boykin, Mathieu Luisier, Gerhard Klimeck Jul 2010

Current Density And Continuity In Discretized Models, Timothy B. Boykin, Mathieu Luisier, Gerhard Klimeck

Birck and NCN Publications

Discrete approaches have long been used in numerical modelling of physical systems in both research and teaching. Discrete versions of the Schr ¨ odinger equation employing either one or several basis functions per mesh point are often used by senior undergraduates and beginning graduate students in computational physics projects. In studying discrete models, students can encounter conceptual difficulties with the representation of the current and its divergence because different finite-difference expressions, all of which reduce to the current density in the continuous limit, measure different physical quantities. Understanding these different discrete currents is essential and requires a careful analysis of the ...


Knudsen Force Modeling In Application To Microsystems, Jeremy S. Nabeth, Sruti Chigullapalli, Alina A. Alexeenko Jul 2010

Knudsen Force Modeling In Application To Microsystems, Jeremy S. Nabeth, Sruti Chigullapalli, Alina A. Alexeenko

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

At the microscale, even moderate temperature differences can result in significant Knudsen forces generated by the energy exchange between gas molecules and solids immersed in a gas. Creating, controlling and measuring Knudsen forces in microsystems can be an arduous task since only limited theory exists at present. This present study investigates the mechanism of Knudsen forces in detail based on numerical solution of the Boltzmann kinetic equation. The Knudsen force is shown, in general, to be a result of thermal nonequilibrium between gas and solid. The simulations are validated by comparison with experimental measurements that have been reported by Passian ...


What Determines Knudsen Force At The Microscale, Jeremy S. Nabeth, Sruti Chigullapalli, Alina A. Alexeenko Jul 2010

What Determines Knudsen Force At The Microscale, Jeremy S. Nabeth, Sruti Chigullapalli, Alina A. Alexeenko

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

Knudsen forces arise in microscale systems when there is a thermal gradient with a characteristic length scale comparable to the molecular mean free path of the ambient gas. These forces are sometimes referred as radiometric or thermo-molecular forces [1] and have been recently measured experimentally in a microscale configuration using heated atomic force microscopy (AFM) probes [2]. The Knudsen force on microstructures with thermal gradients can provide a novel actuation mechanism for mass detection, thermogravimetry, and very high-resolution heat flux measurements. While measuring such forces precisely at microscale can be an arduous task especially since only limited analytical results exist ...


High Performance Atomic-Layer-Deposited Laluo3/Ge-On-Insulator P-Channel Metal-Oxide-Semiconductor Field-Effect Transistor With Thermally Grown Geo2 As Interfacial Passivation Layer, J J. Gu, Y Q. Liu, M Xu, G K. Celler, R G. Gordon, P. D. Ye Jul 2010

High Performance Atomic-Layer-Deposited Laluo3/Ge-On-Insulator P-Channel Metal-Oxide-Semiconductor Field-Effect Transistor With Thermally Grown Geo2 As Interfacial Passivation Layer, J J. Gu, Y Q. Liu, M Xu, G K. Celler, R G. Gordon, P. D. Ye

Birck and NCN Publications

Enhancement-mode p-channel metal-oxide-semiconductor field-effect transistor (MOSFET) on germanium-on-insulator substrate is fabricated with atomic-layer-deposited (ALD) LaLuO3 as gate dielectric. Significant improvement in both on-state current and effective hole mobility has been observed for devices with thermal GeO2 passivation. The negative threshold voltage (V-T) shift in devices with GeO2 interfacial layer (IL) further demonstrates the effectiveness of surface passivation. Results from low temperature mobility characterization show that phonon scattering is the dominant scattering mechanism at a large inversion charge, indicating good interface quality. The combination of higher-k LaLuO3 and ultrathin GeO2 IL is a promising solution to the tradeoff between the aggressive ...


Numerical Approach For Quantification Of Epistemic Uncertainty, John Jakeman, Michael Eldred, Dongbin Xiu Jun 2010

Numerical Approach For Quantification Of Epistemic Uncertainty, John Jakeman, Michael Eldred, Dongbin Xiu

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

In the field of uncertainty quantification, uncertainty in the governing equations may assume two forms: aleatory uncertainty and epistemic uncertainty. Aleatory uncertainty can be characterised by known probability distributions whilst epistemic uncertainty arises from a lack of knowledge of probabilistic information. While extensive research efforts have been devoted to the numerical treatment of aleatory uncertainty, little attention has been given to the quantification of epistemic uncertainty. In this paper, we propose a numerical framework for quantification of epistemic uncertainty. The proposed methodology does not require any probabilistic information on uncertain input parameters. The method only necessitates an estimate of the ...


Naturally Occurring Nanoparticles From English Ivy: An Alternative To Metal-Based Nanoparticles For Uv Protection, Lijin Xia, Scott C. Lenaghan, Mingjun Zhang, Zhili Zhang, Quanshui Li Jun 2010

Naturally Occurring Nanoparticles From English Ivy: An Alternative To Metal-Based Nanoparticles For Uv Protection, Lijin Xia, Scott C. Lenaghan, Mingjun Zhang, Zhili Zhang, Quanshui Li

Faculty Publications and Other Works -- Mechanical & Aerospace Engineering/Engineering Science (MAES) (UTSI)

Background

Over the last decade safety concerns have arisen about the use of metal-based nanoparticles in the cosmetics field. Metal-based nanoparticles have been linked to both environmental and animal toxicity in a variety of studies. Perhaps the greatest concern involves the large amounts of TiO2 nanoparticles that are used in commercial sunscreens. As an alternative to using these potentially hazardous metal-based nanoparticles, we have isolated organic nanoparticles from English ivy (Hedera helix). In this study, ivy nanoparticles were evaluated for their potential use in sunscreens based on four criteria: 1) ability to absorb and scatter ultraviolet light, 2) toxicity ...


Puremd Manual (Purdue Reactive Molecular Dynamics Program), Hasan Metin Aktulga Jun 2010

Puremd Manual (Purdue Reactive Molecular Dynamics Program), Hasan Metin Aktulga

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

No abstract provided.


Strain Rate Sensitivity Of Nanocrystalline Au Films At Room Temperature, K Jonnalagadda, N Karanjgaokar, Joo Lien Chee, Dimitrios Peroulis Jun 2010

Strain Rate Sensitivity Of Nanocrystalline Au Films At Room Temperature, K Jonnalagadda, N Karanjgaokar, Joo Lien Chee, Dimitrios Peroulis

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

The effect of strain rate on the inelastic properties of nanocrystalline Au films was quantified with 0.85 and 1.76 lm free-standing microscale tension specimens tested over eight decades of strain rate, between 6 106 and 20 s1. The elastic modulus was independent of the strain rate, 66 ± 4.5 GPa, but the inelastic mechanical response was clearly rate sensitive. The yield strength and the ultimate tensile strength increased with the strain rate in the ranges 575–895 MPa and 675–940 MPa, respectively, with the yield strength reaching the tensile strength at strain rates faster than 101 s1 ...


On The Bandstructure Velocity And Ballistic Current Of Ultra-Narrow Silicon Nanowire Transistors As A Function Of Cross Section Size, Orientation, And Bias, Neophytos Neophytou, Sung-Geun Kim, Gerhard Klimeck, Hans Kosina Jun 2010

On The Bandstructure Velocity And Ballistic Current Of Ultra-Narrow Silicon Nanowire Transistors As A Function Of Cross Section Size, Orientation, And Bias, Neophytos Neophytou, Sung-Geun Kim, Gerhard Klimeck, Hans Kosina

Birck and NCN Publications

A 20 band sp(3)d(5)s* spin-orbit-coupled, semiempirical, atomistic tight-binding model is used with a semiclassical, ballistic field-effect-transistor model, to theoretically examine the bandstructure carrier velocity and ballistic current in silicon nanowire (NW) transistors. Infinitely long, uniform, cylindrical, and rectangular NWs, of cross sectional diameters/sides ranging from 3-12 nm are considered. For a comprehensive analysis, n-type and p-type metal-oxide semiconductor (NMOS and PMOS) NWs in [100], [110], and [111] transport orientations are examined. In general, physical cross section reduction increases velocities, either by lifting the heavy mass valleys or significantly changing the curvature of the bands. The ...