Nanoscience and Nanotechnology Commons^™

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

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

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 …

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

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. The activation volumes for …

Boron Carbide Based Solid State Neutron Detectors: The Effects Of Bias And Time Constant On Detection Efficiency, Nina Hong, John Mullins, Keith Foreman, Shireen Adenwalla

Shireen Adenwalla Papers

Neutron detection in thick boron carbide(BC)/n-type Si heterojunction diodes shows a threefold increase in efficiency with applied bias and longer time constants. The improved efficiencies resulting from long time constants have been conclusively linked to the much longer charge collection times in the BC layer. Neutron detection signals from both the p-type BC layer and the n-type Si side of the heterojunction diode are observed, with comparable efficiencies. Collectively, these provide strong evidence that the semiconducting BC layer plays an active role in neutron detection, both in neutron capture and in charge generation and collection.

The Characterization And Analysis Of In-Vitro And Elevated Temperature Repassivation Of Ti-6al-4v Via Afm Techniques, Aaron J. Guerrero

Master's Theses

ABSTRACT

The Characterization and Analysis of In-vitro and Elevated Temperature Repassivation of

Ti-6Al-4V via AFM Techniques

Aaron J Guerrero

Research in the corrosion of orthopaedic implants is a growing research field where implants have been known to show adverse effects in patients who have encountered the unfortunate dissolution of their implants due to corrosion. Once corrosion begins within the body, many adverse biological reactions can occur such as late on-set infections resulting in severe health complications. The focus of this research is specifically related to the problem of late on-set infections caused by localized corrosion of orthopaedic implants. In medical …

The Applications And Limitations Of Printable Batteries, Matthew Delmanowski

Graphic Communication

This study focuses on the potential applications for printed batteries and how they could affect the printing industry. It also analyzes the main problems associated with manufacturing this technology and what needs to be done to overcome these issues. To find the answers to these questions, two methods of research were used. The first was through the elite and specialized interviewing of Dr. Scott Williams of Rochester Institute of Technology and Professor Nancy Cullins from Cal Poly. The second form of research was a common, yet useful, method called secondary research. This entailed looking at recent written research papers about …

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 carrier velocities of PMOS [110] …

The Impact Of Nonlinearity On Degenerate Parametric Amplifiers, Jeff Rhoads, Steven W. Shaw

Birck and NCN Publications

This work investigates the effects of system nonlinearities on degenerate parametric amplifiers. A simple, Duffing-type nonlinearity is appended to a representative equation of motion for a mechanical or electromechanical parametric amplifier, and classical perturbation methods are used to characterize the resulting effects on the amplifier's frequency response and performance. Ultimately, the work demonstrates that parametric amplification can be realized in nonlinear, dynamic-range limited systems, such as resonant micro-or nanosystems, but at the expense of performance degradation. Additionally, it is shown that nonlinear amplifiers can be operated above their linear instability threshold but that doing so results in bistable amplified responses.

Ambipolar Graphene Field Effect Transistors By Local Metal Side Gates, J F. Tian, L A. Jauregui, G Lopez, H Cao, Yong P. Chen

Birck and NCN Publications

We demonstrate ambipolar graphene field effect transistors individually controlled by local metal side gates. The side gated field effect can have on/off ratio comparable with that of the global back gate, and can be tuned in a large range by the back gate and/or a second side gate. We also find that the side gated field effect is significantly stronger by electrically floating the back gate compared to grounding the back gate, consistent with the finding from electrostatic simulation.

Enhanced Light Extraction Efficiency From Gan Light Emitting Diodes Using Photonic Crystal Grating Structures, Simeon S. Trieu

Master's Theses

Gallium nitride (GaN) light emitting diodes (LED) embody a large field of research that aims to replace inefficient, conventional light sources with LEDs that have lower power, higher luminosity, and longer lifetime. This thesis presents an international collaboration effort between the State Key Laboratory for Mesoscopic Physics in Peking University (PKU) of Beijing, China and the Electrical Engineering Department of California Polytechnic State University, San Luis Obispo. Over the course of 2 years, Cal Poly’s side has simulated GaN LEDs within the pure blue wavelength spectrum (460nm), focusing specifically on the effects of reflection gratings, transmission gratings, top and bottom …

Nanoscale Metal-Metal Contact Physics From Molecular Dynamics: The Strongest Contact Size, Hojin Kim, Alejandro Strachan

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

Using molecular dynamics we find that the tensile strength of the contacts between two clean platinum surfaces with nanoscale asperities is strongly size dependent with a maximum strength for contact lengths of approximately 5 nm. This is the first time a strongest size is observed in single crystals. The strengthening with decreasing size down to 5 nm results from a decrease in the initial density of mobile dislocations available for plastic deformation and the subsequent weakening originates from a reduction in the constraint to mechanical deformation inside the contact by the bulk.

Nano/Micro-Structured Electrode Materials For Lithium-Ion Batteries, Yu-Guo Guo, Zhong-Li Wang, Xing-Long Wu, Wei-Ming Zhang, Li-Jun Wan

Journal of Electrochemistry

Nanostructured materials are currently of interest as high performance anodes and cathodes for rechargeable lithium-ion batteries because of their novel nano-size effects and significantly enhanced kinetics. This review paper describes some recent developments in this field,addressing the size effects,morphology effects,as well as the functions of carbon coating layers toward lithium storage. Several"kinetically stabilized"nano/microstructured electrode materials and high-rate electrode materials with mixed-conducting networks based on the work of the authors are highlighted for illustration.

Electrocatalytic Oxidation Of Hcooh At Au(Core)-Pd(Shell)-Pt(Cluster) Nanocubes, Qing-Ning Jiang, Huan Li, Ning Yang, Ping-Ping Fang, Feng-Ru Fan, Zhong-Qun Tian

Journal of Electrochemistry

Gold nanocubes were synthesized by a two-step seed-mediated growth method. The Aucore-Pdshell and Au_core-Pd_shell-Pt_cluster nanocubes with controllable shell thickness of Pd and cluster coverage of Pt were synthesized by simply changing the amount ratio of H₂PdCl₄ or H₂PtCl₆. The samples were characterized by scanning electron microscope (SEM) , transmission electron microscopc (TEM) and cyclic voltammetry (CV). CV was then used to make a systematic study on the dependence of the electrocatalytic properties on the shell thickness of Au_core-Pd_shell and Pt coverage of Au_core-Pd …

Prerapation And Supercapacitor Property Of Mesoporous Carbon Nanofibers, Yong-Wen Wang, Ming-Bo Zheng, Jian Cao, Jie-Ming Cao, Guang-Bin Ji, Jie Tao

Journal of Electrochemistry

Two different mesoporous carbon nanofibers with large mesopore or core-shell structure were prepared by using the resol/F127 mixture to fill the AAO template. The morphology and structural parameters of the samples were characterized by SEM,TEM,and N₂ adsorption-desorption analysis. The supercapacitive behaviors of the electrodes were tested by cyclic voltammetry and galvanostatic charge-discharge. The results show that the specific capacitances of mesoporous carbon nanofibers increased obviously and the fine supercapacitive performances were achieved at high scan rate or large current density.

Nano-Sized Au On Nickel Foam As Cathode Of Alkaline Al-H2O2 Semi Fuel Cell, Shu-Li Chen, Bang-An Lu, Yao Liu, Gui-Ling Wang, Dian-Xue Cao

Journal of Electrochemistry

Nano-sized Au particles were deposited on a nickel foam substrate by a fast spontaneous deposition method using AuCl₃ as the source of Au. The effects of AuCl₃ concentration and deposition time on the size and distribution of Au particles,and the performance of the obtained Au/Ni electrode as the cathode of Al-H₂O₂ semi fuel cell were investigated. It was found that after the nickel foam was immersed in a 2 mmol·L^-1 AuCl₃ solution for 60 s,Au particles with diameters smaller than 100 nm were deposited on its surfaces and cover the surface completely. The …

A Reactive Molecular Dynamics Simulation Of The Silica-Water Interface, Joseph C. Fogarty, Hasan Metin Aktulga, Ananth Y. Grama, Adri C. T. Van Duin, Sagar A. Pandit

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

We report our study of a silica-water interface using reactive molecular dynamics. This first-of-its-kind simulation achieves length and time scales required to investigate the detailed chemistry of the system. Our molecular dynamics approach is based on the ReaxFF force field of van Duin [J. Phys. Chem. A 107, 3803 (2003)]. The specific ReaxFF implementation (SERIALREAX) and force fields are first validated on structural properties of pure silica and water systems. Chemical reactions between reactive water and dangling bonds on a freshly cut silica surface are analyzed by studying changing chemical composition at the interface. In our simulations, reactions involving silanol …

Experimental Observation Of The Trapped Rainbow, Vera N. Smolyaninova, Igor Smolyaninov, Alexander V. Kildishev, V. M. Shalaev

Birck and NCN Publications

We report on the experimental demonstration of the broadband "trapped rainbow" in the visible frequency range using an adiabatically tapered optical nano waveguide. Being a distinct case of the slow light phenomenon, the trapped rainbow effect could be applied to optical computing and signal processing, such as spectroscopy on a chip, and to providing enhanced light-matter interactions. (C) 2010 American Institute of Physics.

Higher-Order Eigenmodes Of Qplus Sensors For High Resolution Dynamic Atomic Force Microscopy, Ryan C. Tung, Thorsten Wutscher, David Martinez-Martin, R. Reifenberger, Franz Giessibl, Arvind Raman

Birck and NCN Publications

The time response of tuning-fork based sensors can be improved by operating them at higher eigenmodes because a measurement takes at least one oscillation cycle in dynamic force microscopy and the oscillation period of the second eigenmode is only about one sixth of the fundamental mode. Here we study the higher-order eigenmodes of quartz qPlus sensors [Bettac et al., Nanotechnology 20, 264009 (2009); Giessibl and Reichling, Nanotechnology 16, S118 (2005); Giessibl, Appl. Phys. Lett. 76, 1470 (2000); and Giessibl, Appl. Phys. Lett. 73, 3956 (1998)], their equivalent stiffness, and piezoelectric sensitivity, while paying special attention to the influence of the …