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CreatorTitleDescriptionSubjectDate
1 Ostafin, AgnesNanomedicine making headway across the blood brain barrierNanotechnological advances implemented by nanomedicine have allowed significant development of imaging strategies, therapeutics and theranostics for many severe and life threatening diseases such as brain tumors, Alzheimer's disease, Parkinson's disease and other neurological disorders. The Blood-Br...2012-01-01
2 Tiwari, AshutoshRoom-temperature solid-state radiation detectors based on spintronicsIn this paper we are presenting a unique approach to solve the thermal background problem encountered in semiconductor nuclear detectors. Our approach addresses above challenge by making a shift from 'electronic detection mechanism' to 'spintronic detection mechanism'. The proposed methodology is ba...2012-01-01
3 Liu, FengElectrochemical measurements on cells, I: Simulation of potential distribution with an embedded probeMeasurements of electric potential in electrochemical devices such as solid oxide fuel cells (SOFC) or solid oxide electrolyzer cells (SOEC) are often made by placing a reference electrode on the surface. Measurement of electric potential with embedded electrodes (probes) has also been reported [1]....2013-01-01
4 Scarpulla, MichaelTemperature dependence of equivalent circuit parameters used to analyze admittance spectroscopy and application to CZTSe devicesWe present a device physics and equivalent circuit model for admittance spectroscopy of CZTSe based photovoltaic devices. The experimental variations of the capacitance and conductance in the depletion width are reproduced for state of the art coevaporated CZTSe devices. We will show that simple Arr...2014-01-01
5 Scarpulla, MichaelInvestigating sputtered Cu2Si1-xSnxS3 (CSTS) for earth abundant thin film photovoltaicsThis study investigates the synthesis of chalcopyrite Cu2Si1-xSnxS3 (CSTS) thin films for photovoltaic solar cell absorber layers. Preliminary results indicate that layered sputtering of Cu, Sn, and Si followed by annealing in a sulfur atmosphere at 500⁰C does not provide adequate mixing or sulfu...2010
6 Scarpulla, MichaelPulsed laser induced ohmic back contact in CdTe solar cellsCreating an ohmic back contact has long been a problem for making efficient CdTe solar cells. Current devices utilize some combination of preferential chemical etching, buffer layer, and Cu doping with additional cost, time, and complexity added for each step. In this Letter, these processes are esc...2014-01-01
7 Stringfellow, Gerald B.; Inglefield, Colin E.; Taylor, P. CraigQuantum wells due to ordering in GaInPCuPt ordering results in a reduction of the band-gap energy of GaInP. Thus, heterostructures and quantum wells can be produced by simply varying the order parameter, without changing the solid composition. Changes in the order parameter can be induced by changes in growth conditions. The disorder...Band-gap energy; Growth temperature; Quantum wells1998-12-28
8 Stringfellow, Gerald B.; Williams, Clayton C.Atomic ordering of GaInP studied by Kelvin probe force microscopyThe atomic ordering of GaInP has been established and studied by a variety of methods, including transmission electron microscopy, cathodoluminescence, and photoluminescence. In this work, a Kelvin probe force microscope _x0002_KPFM_x0003_ has been employed to image several GaInP samples previous...Cathodoluminescence; Photoluminescence; Surface morphology1995
9 Scarpulla, MichaelThe importance of Se partial pressure in the laser annealing of CuInSe2 electrodeposited precursorsOne method for producing CuInSe2 (CISe) absorber layers is electrodeposition followed by annealing. Replacing the commonly used furnace annealing step with a laser can reduce annealing times by 2-3 orders of magnitude: from 30 minutes to 1 s. However, laser processing has, to date, not resulted in a...2014-01-01
10 Stringfellow, Gerald B.; Williams, Clayton C.Spatial mapping of ordered and disordered domains of GaInP by near-field scanning optical microscopy and scanning capacitance microscopyImaging of topography, locally induced photoluminescence and Fermi-level pinning in adjacent ordered and disordered domains on a cleaved GaInP sample is performed using a near-field scanning optical microscope and scanning capacitance microscope at room temperature in air. Highly localized photolumi...Gallium Phosphides; Surface Structure; Photoluminescence1996-04-13
11 Liu, FengBending of nanoscale thin Si film induced by growth of Ge islands: hut vs. domeWe perform atomistic simulations to compute bending of freestanding nanoscale thin Si film induced by strained Ge islands. We show that a larger Ge dome island can induce smaller bending than a smaller hut island and explain the surprising experimental observation for growth of Ge islands on pattern...Bending; Nanoscale thin Si film; Ge islands; Hut islands; Dome islands; Atomistic simulations2004
12 Stringfellow, Gerald B.; Sadwick, Laurence P.Low pressure pyrolysis of alternate phosphorus precursors for chemical beam epitaxial growth of InP and related compoundsThe most widely used phosphorous source in chemical beam epitaxy (CBE) is phosphine (PH3). However, because it is highly toxic, alternatives to phosphine have been sought for the growth of phosphorous-containing compounds. We have investigated the pyrolysis rates and reaction products, in low pres...Chemical Beam Epitaxy; CBE1994
13 Scarpulla, MichaelTe-rich CdTe surface by pulsed UV laser treatment for ohmic back contact formationPulsed UV laser treatments have recently been applied to polycrystalline CdTe solar cells to create an ohmic back contact. In this work, we investigate the surface stoichiometry variations produced by pulsed laser excitation using X-ray photoelectron spectroscopy (XPS). These results reveal surfaces...2014-01-01
14 Scarpulla, MichaelGrain size and texture of Cu2ZnSnS4 thin films synthesized by co-sputtering binary sulfides and annealing: effects of processing conditions and sodiumWe investigate the synthesis of kesterite Cu2ZnSnS4 (CZTS) polycrystalline thin films using cosputtering from binary sulfide targets followed by annealing in sulfur vapor at 500 ?C to 650 ?C. The films are the kesterite CZTS phase as indicated by x-ray diffraction, Raman scattering, and optical abso...2011
15 Liu, FengSeeing the atomic orbital: first-principles study of the effect of tip termination on atomic force microscopyWe perform extensive first-principles calculations to simulate the topographical atomic-force-microscope image of an adatom on the Si(111)-(7 X 7) surface, demonstrating the feasibility of imaging not only the atoms but also the atomic orbitals. Our comparative study of tip terminations shows that ...First-principles; Tip termination; Adatoms2003-06
16 Chaudhuri, Reaz A.Three-dimensional singular stress field at the front of a crack and lattice crack deviation (LCD) in a cubic single crystal plateA novel eigenfunction expansion technique, based in part on separation of the thickness variable, is developed to derive three-dimensional asymptotic stress fields in the vicinity of the front of a semi-infinite through-crack weakening an infinite plate made of a homogeneous cubic single crystal. C...2010-05-12
17 Pugmire, Ronald J.Soot formation during coal pyrolysisSoot can be found in almost all combustion and pyrolysis systems. In a coal system, the impact of soot on coal combustion can be identified in two ways. First, soot particles suspended in the combustion flame significantly enhance radiative heat transfer near the burner due to their large surface ar...2001
18 Liu, FengGeometric constant defining shape transitions of carbon nanotubes under pressureWe demonstrate that when a single-walled carbon nanotube is under pressure it undergoes a series of shape transitions, first transforming from a circle to an oval and then from an oval to a peanut. Most remarkably, the ratio of the area of the tube cross sections at the second transition over that ...Geometric constant; Shape transitions; Carbon nanotubes; Pressure2004-03
19 Liu, FengDetermination of the Ehrlich-Schwoebel barrier in epitaxial growth of thin filmsWe demonstrate an approach for determining the "effective" Ehrlich-Schwoebel (ES) step-edge barrier, an important kinetic constant to control the interlayer mass transport in epitaxial growth of thin films. The approach exploits the rate difference between the growth and/or decay of an adatom and a...Ehrlich-Schwoebel barrier; Epitaxial growth; Step-edge barrier; Adatoms2006-11
20 Liu, FengEffects of Li doping on H-diffusion in MgH2: A first-principles studyThe effects of Li doping in MgH2 on H-diffusion process are investigated, using first-principles calculations. We have identified two key effects: (1) The concentration of H vacancy in the þ1 charge state ðVþ1 H Þ can increase by several orders of magnitude upon Li doping, which significantly in...2013-01-01
21 Scarpulla, MichaelTemperature dependent conductivity of polycrystalline Cu 2ZnSnS 4 thin filmsThe temperature-dependent conductivity of Cu2ZnSnS4 (CZTS) thin films prepared by sulfurization of different sputtered ZnS/Cu/Sn stacks and also of the same stack annealed for different times was investigated from 30-300 K. Fitting of the through-thickness conductivity requires a model including Mot...2012-01-01
22 Stringfellow, Gerald B.Effect of oxygen incorporation in semi-insulating (AlxGa1-x)yIn1-yPDiscusses a study conducted on oxygen-doped, semi-insulating layers of (aluminum-gallium) indium phosphide grown on gallium arsenide using organometallic vapor phase epitaxy. Effect of oxygen doping on semi-insulating layers of the substance; Secondary-ion mass spectrometry measurements; Measured co...Inactive interstitial atoms; Energy-dispersive spectoscopy; intentional oxygen1992
23 Tiwari, AshutoshGarnet-type Li7La3Zr2O12 electrolyte prepared by a solution-based technique for lithium ion batteryHigh quality garnet-type Li7La3Zr2O12 solid electrolyte was synthesized using a solution-based technique. The electrolyte pellets were sintered at 900 oC, resulting in tetragonal phase, which then transformed to cubic phase after annealing at 1230 oC. The ionic conductivity of both phases was studie...2012-01-01
24 Tiwari, AshutoshModification of high potential, high capacity Li2FeP 2O7 cathode material for lithium ion batteriesLi2FeP2O7 is a newly developed polyanionic cathode material for high performance lithium ion batteries. It is considered very attractive due to its large specific capacity, good thermal and chemical stability, and environmental benignity. However, the application of Li2FeP2O7 is limited by its low i...2012-01-01
25 Smith, Grant D.Molecular dynamics simulation studies of the influence of imidazolium structure on the properties of imidazolium/azide ionic liquidsAtomistic molecular dynamics simulations were performed on 1-butyl-3-methyl-imidazolium azide [bmim][N3], 1-butyl-2,3-dimethylimidazolium azide [bmmim][N3], and 1-butynyl-3-methylimidazolium azide [bumim][N3] ionic liquids. The many-body polarizable APPLE&P force field was augmented with parameters ...2012-01-01
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