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Filters: Department: "Materials Science & Engineering" Format: "application/pdf" School Or College: "College of Engineering" Collection: "ir_uspace"
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CreatorTitleDescriptionSubjectDate
1 Liu, Feng(BAl12)Cs: a cluster-assembled solidFirst-principles calculations on the geometry and stability of AlnBm clusters have been carried out to examine the effect of size, composition, and electronic-shell filling on their relative stability. It is shown that although Al and B are both trivalent, a BAl12 cluster is more stable than an Al1...First-principles calculations; (BAl12)Cs; Cluster-assembled; AlnBm clusters1997-06
2 Liu, FengA three-layer-mesh bridging domain for coupled atomistic-continuum simulations at finite temperature: formulation and testingAlthough concurrent multiscale methods have been well developed for zero-temperature simulations, improvements are needed to meet challenges pertaining to finite-temperature simulations. Bridging domain method (BDM) is one of the most efficient and widely-used multiscale atomistic-continuum techniqu...2014-01-01
3 Stringfellow, Gerald B.; Shurtleff, James KevinAdsorption and desorption of the surfactant Sb on GaInP grown by organometallic vapor phase epitaxyIt has been determined that ordering has a profound effect on the bandgap energy of many compound semiconductor alloys. Therefore, ordering must be controlled for devices such as solar cells, light emitting diodes and diode lasers. Since ordering depends on the surface properties during organomet...Time dependent surface photoabsorption (SPA); Compound semiconductor alloys2000
4 Scarpulla, MichaelAir shear driven flow of thin perfluoropolyether polymer filmsWe have studied the wind driven movement of thin perfluoropolyether (PFPE) polymer films on silicon wafers and CNx overcoats using the blow-off technique. The ease with which a liquid polymer film moves across a surface when sheared is described by a shear mobility xS , which can be interpreted both...Perfluoropolyether; Polymer films; Air shear; Shear mobility2003
5 Liu, FengAnisotropic strain enhanced hydrogen solubility in bcc metals: the independence on the sign of strainWhen an impurity is doped in a solid, it inevitably induces a local stress, tending to expand or contract the lattice. Consequently, strain can be applied to change the solubility of impurity in a solid. Generally, the solubility responds to strain ‘‘monotonically,'' increasing (decreasing) with...2012-01-01
6 Bedrov, Dmitro; Smith, Grant D.Anomalous pressure dependence of the structure factor in 1,4-polybutadiene melts: a molecular dynamics simulation studyNeutron scattering has shown the first diffraction peak in the structure factor of a 1,4-polybutadiene melt under compression to move to larger q values as expected but to decrease significantly in intensity. Simulations reveal that this behavior does not result from loss of structure in the polymer...Polymer melts; 1, 4-polybutadiene melts; Pressure; Structure factor2004-07
7 Stringfellow, Gerald B.Atomic force microscopy study of ordered GaInPExamines the nature of the steps on the surface of gallium indium phosphide lattice layers matched to gallium arsenide substrates using atomic force microscopy. Temperatures of organometallic vapor phase epitaxy used; Relation of height of steps with misorientation angle; Link of supersteps with the...Surface chemistry; Lattice theory1995
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 Tiwari, AshutoshBand-gap engineering of Zn1-xGaxO nanopowders: synthesis, structural and optical characterizationsWe report the preparation and detailed structural and optical characterizations of single phase gallium doped ZnO nanopowders. A low temperature solution-based technique was developed to synthesize high-purity Zn1−xGaxO (x:0-0.05) nanopowders. Structural and optical characterization experiments we...Zinc gallium oxide; ZnGaO; Nanopowders; Band-gap engineering2008
10 Scarpulla, MichaelBandgap and band offsets determination of semiconductor heterostructures using three-terminal ballistic carrier spectroscopyAmong the most important properties of semiconductors are their bandgaps and how the total bandgap difference distributes between the conduction band offset ΔEC and the valence band offset ΔEV at the heterojunction (HJ) interface between two semiconductors. Understanding such properties is crucial...Bandgaps; Band offsets; Gallium arsenide2009
11 Stringfellow, Gerald B.Bandgap control of GaInP using Sb as a surfactantThe use of surfactants to control specific aspects of the vapor-phase epitaxial growth process is beginning to be studied for both the elemental and III/V semiconductors. To date, most reported surfactant effects for semiconductors relate to the morphology of the growing films. However, semicondu...Band-gap energy; Growth process; Epitaxial growth1999-09-27
12 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
13 Liu, FengBending of nanoscale ultrathin substrates by growth of strained thin films and islandsMechanical bending is ubiquitous in heteroepitaxial growth of thin films where the strained growing film applies effectively an "external" stress to bend the substrate. Conventionally, when the deposited film is much thinner than the substrate, the bending increases linearly with increasing film th...Nanoscale ultrathin substrates; Strained thin films; Islands; Heteroepitaxial growth; Si substrate; Ge film2005-08
14 Stringfellow, Gerald B.Bi surfactant control of ordering and surface structure in GaInP grown by organometallic vapor phase epitaxyStudies the effect of the surfactant bismuth on the ordering and surface structure in GaInP layers grown by organometallic vapor phase epitaxy. Disordering caused by the addition of bismuth during growth; Changes in surface structure occurring with the disordering.Thin films, Multilayered; Bismuth2000
15 Stringfellow, Gerald B.; Shurtleff, James KevinBi surfactant effects on ordering in GaInP grown by organometallic vapor-phase epitaxyThe effect of the isoelectronic surfactant Bi on surface structure and ordering has been studied for GaInP semiconductor alloys grown by organometallic vapor-phase epitaxy. A small amount of Bi trimethylbismuth added during growth is found to result in disordering for layers grown using conditions t...Surfactant; Semiconductors; Trimethylbismuth2000
16 Scarpulla, MichaelCarrier concentration dependencies of magnetization & transport in Ga1-xMnxAs1-yTeyWe have investigated the transport and magnetization characteristics of Ga1-xMnxAs intentionally compensated with shallow Te donors. Using ion implantation followed by pulsed-laser melting, we vary the Te compensation and drive the system through a metal-insulator transition (MIT). This MIT is assoc...Gallium arsenide; Ferromagnetic semiconductors; Magnetization; Resistivity2005
17 Tiwari, AshutoshCharacterization of Li7La3Zr2O 12 thin films prepared by pulsed laser depositionA pulsed laser deposition system was employed to fabricate thin films of Li7La3Zr2O12 solid electrolyte. The deposition process was carried out at room-temperature, resulting in amorphous films. These as-deposited films had a large optical band gap of 5.13 eV, and exhibited a lithium-ion conductivit...2012-01-01
18 Stringfellow, Gerald B.;Inglefield, Colin E.;Taylor, P. CraigCharacterization of unicompositional GaInP2 ordering heterostructures grown by variation of V/III ratioPhotoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies are employed to investigate single heterostructures based on two GaInP2 layers that have the same composition but different degrees of order on the cation sublattice. Four sample configurations are studied: two complemen...Heterostructures; Growth parameters; Growth temperature1997
19 Ostafin, AgnesCombined deletion of mouse dematin-headpiece and ß-adducin exerts a novel effect on the spectrin-actin junctions leading to erythrocyte fragility and hemolytic AnemiaDematin and adducin are actin-binding proteins of the erythrocyte "junctional complex." Individually, they exert modest effects on erythrocyte shape and membrane stability, and their homologues are expressed widely in non-erythroid cells. Here we report generation and characterization of double knoc...2007
20 Bedrov, Dmitro; Smith, Grant D.Comparison of self-assembly in lattice and off-lattice model amphiphile solutionsLattice Monte Carlo and off-lattice molecular dynamics simulations of h1t4 and h4t1 (head/tail) amphiphile solutions have been performed as a function of surfactant concentration and temperature. The lattice and off-lattice systems exhibit quite different self-assembly behavior at equivalent ther...Amphiphile solutions; Micellization; Surfactants2002
21 Scarpulla, MichaelCompensation-dependent in-plane magnetization reversal processes in Ga1-xMnxP1-ySyWe report the effect of dilute alloying of the anion sublattice with S on the in-plane uniaxial magnetic anisotropy and magnetization reversal process in Ga1−xMnxP as measured by both ferromagnetic resonance (FMR) spectroscopy and superconducting quantum interference device (SQUID) magnetometry. ...Ferromagnetic semiconductors; Nonmagnetic compensation2008-12
22 Scarpulla, MichaelCompositional tuning of ferromagnetism in Ga1-xMnxPWe report the magnetic and transport properties of Ga1-xMnxP synthesized via ion implantation followed by pulsed laser melting over a range of x, namely 0.018 to 0.042. Like Ga1-xMnxAs, Ga1-xMnxP displays a monotonic increase of the ferromagnetic Curie temperature with x associated with the hole-me...Gallium arsenide; Ferromagnetic semiconductors2006-12
23 Liu, FengComputational designing of carbon nanotube electromechanical pressure sensorsWe investigate electronic transport properties of single-walled carbon nanotubes (SWNT's) under hydrostatic pressure, using first-principles quantum transport calculations aided by molecular-dynamics simulation and continuum mechanics analysis. We demonstrate a pressure-induced metal-to-semiconduc...Carbon nanotubes; Computational designing; Pressure sensors; Electronic transport2004-04
24 Liu, FengComputational R&D for industrial applicationsRecent advances in high-speed supercomputer and computational algorithms have brought us into a new era of computational materials science. These advances make it possible to investigate many existing materials systems that were previously considered intractable and also predict and design novel mat...Computational materials science2005
25 Liu, FengConfining P diffusion in Si by an As-doped barrier layerThe miniaturization of Si-based devices requires control of doping profile, which makes the understanding of dopant interaction and diffusion in Si critical. The authors have studied the effect of As doping on P diffusion in Si using first-principles calculations. The authors found a form of As-vaca...P diffusion; Silicon; Arsenic doping; As-doped barrier; Diffusion control2007
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