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Creator | Title | Description | Subject | Date |
| 1 |
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Liu, Feng | (BAl12)Cs: a cluster-assembled solid | First-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 clusters | 1997-06 |
| 2 |
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Smith, Grant D.; Borodin, Oleg; Bedrov, Dmitro | 13C NMR spin-lattice relaxation and conformational dynamics in a 1,4-polybutadiene melt | We have performed molecular dynamics (MD) simulations of a melt of 1,4-polybutadiene (PBD, 1622 Da) over the temperature range 400?273 K. 13C NMR spin?lattice relaxation times (T1) and nuclear Overhauser enhancement (NOE) values have been measured from 357 to 272 K for 12 different resonances. The T... | Polybutadiene melt; 13C NMR; Spin-lattice relaxation; Conformational dynamics; Molecular dynamics simulation | 2001 |
| 3 |
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Liu, Feng | A three-layer-mesh bridging domain for coupled atomistic-continuum simulations at finite temperature: formulation and testing | Although 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 |
| 4 |
 |
Stringfellow, Gerald B.; Shurtleff, James Kevin | Adsorption and desorption of the surfactant Sb on GaInP grown by organometallic vapor phase epitaxy | It 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 alloys | 2000 |
| 5 |
 |
Scarpulla, Michael | Air shear driven flow of thin perfluoropolyether polymer films | We 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 mobility | 2003 |
| 6 |
 |
Liu, Feng | Anisotropic strain enhanced hydrogen solubility in bcc metals: the independence on the sign of strain | When 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 |
| 7 |
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Bedrov, Dmitro; Smith, Grant D. | Anomalous pressure dependence of the structure factor in 1,4-polybutadiene melts: a molecular dynamics simulation study | Neutron 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 factor | 2004-07 |
| 8 |
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Stringfellow, Gerald B. | Atomic force microscopy study of ordered GaInP | Examines 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 theory | 1995 |
| 9 |
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Stringfellow, Gerald B.; Williams, Clayton C. | Atomic ordering of GaInP studied by Kelvin probe force microscopy | The 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 morphology | 1995 |
| 10 |
 |
Tiwari, Ashutosh | Band-gap engineering of Zn1-xGaxO nanopowders: synthesis, structural and optical characterizations | We 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 engineering | 2008 |
| 11 |
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Scarpulla, Michael | Bandgap and band offsets determination of semiconductor heterostructures using three-terminal ballistic carrier spectroscopy | Among 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 arsenide | 2009 |
| 12 |
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Stringfellow, Gerald B. | Bandgap control of GaInP using Sb as a surfactant | The 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 growth | 1999-09-27 |
| 13 |
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Liu, Feng | Bending of nanoscale thin Si film induced by growth of Ge islands: hut vs. dome | We 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 simulations | 2004 |
| 14 |
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Liu, Feng | Bending of nanoscale ultrathin substrates by growth of strained thin films and islands | Mechanical 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 film | 2005-08 |
| 15 |
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Stringfellow, Gerald B. | Bi surfactant control of ordering and surface structure in GaInP grown by organometallic vapor phase epitaxy | Studies 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; Bismuth | 2000 |
| 16 |
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Stringfellow, Gerald B.; Shurtleff, James Kevin | Bi surfactant effects on ordering in GaInP grown by organometallic vapor-phase epitaxy | The 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; Trimethylbismuth | 2000 |
| 17 |
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Scarpulla, Michael | Carrier concentration dependencies of magnetization & transport in Ga1-xMnxAs1-yTey | We 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; Resistivity | 2005 |
| 18 |
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Tiwari, Ashutosh | Characterization of Li7La3Zr2O 12 thin films prepared by pulsed laser deposition | A 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 |
| 19 |
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Stringfellow, Gerald B.;Inglefield, Colin E.;Taylor, P. Craig | Characterization of unicompositional GaInP2 ordering heterostructures grown by variation of V/III ratio | Photoluminescence (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 temperature | 1997 |
| 20 |
 |
Ostafin, Agnes | Combined deletion of mouse dematin-headpiece and ß-adducin exerts a novel effect on the spectrin-actin junctions leading to erythrocyte fragility and hemolytic Anemia | Dematin 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 |
| 21 |
|
Bedrov, Dmitro; Borodin, Oleg; Smith, Grant D. | Comment on "On the accuracy of force fields for predicting the physical properties of dimethylnitramine" | Zheng and Thompson have recently reported a comparison of three atomistic force fields for prediction of physical properties of dimethylnitramine (DMNA) from molecular dynamics (MD) simulations.1 Specifically, they compared the rigid molecule force field by Sorescu, Rice, and Thompson (SRT);2 the ge... | | 2007 |
| 22 |
 |
Bedrov, Dmitro; Smith, Grant D. | Comparison of self-assembly in lattice and off-lattice model amphiphile solutions | Lattice 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; Surfactants | 2002 |
| 23 |
 |
Scarpulla, Michael | Compensation-dependent in-plane magnetization reversal processes in Ga1-xMnxP1-ySy | We 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 compensation | 2008-12 |
| 24 |
 |
Scarpulla, Michael | Compositional tuning of ferromagnetism in Ga1-xMnxP | We 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 semiconductors | 2006-12 |
| 25 |
 |
Liu, Feng | Computational designing of carbon nanotube electromechanical pressure sensors | We 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 transport | 2004-04 |
| 26 |
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Liu, Feng | Computational R&D for industrial applications | Recent 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 science | 2005 |
| 27 |
 |
Liu, Feng | Confining P diffusion in Si by an As-doped barrier layer | The 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 control | 2007 |
| 28 |
|
Smith, Grant D. | Conformational properties of poly(vinylidene fluoride). A quantum chemistry study of model compounds | The molecular geometries and conformational energies of model molecules of poly(vinylidene fluoride) (PVDF) have been determined from high-level quantum chemistry calculations and have been used in parametrization of a six-state rotational isomeric state (RIS) model for PVDF. The model molecules inv... | Poly(vinylidene fluoride); PVDF; Conformational properties | 1999 |
| 29 |
 |
Stringfellow, Gerald B. | Control and characterization of ordering in GaInP | Gae,,In,,P layers have been grown by organometallic vapor phase epitaxy on GaAs substrates with [llO]-oriented grooves on the surface that have an important effect on the formation of Cu-Pt ordered structures during growth. In this work, the groove shape is demonstrated to be critically important... | Vapor phase epitaxy; Ordered structure; Cathodoluminescence spectroscopy | 1993-06-28 |
| 30 |
 |
Stringfellow, Gerald B. | Control of ordering in Ga0.5In0.5P using growth temperature | The kinetic processes leading to ordering in Gas,, In o.4P8 have been studied by observing the effects of substrate misorientation (O-9), growth rate (0.1-0.5), and substrate temperature (570- 670 "C) during growth. The ordered structure and degree of ordering are determined using transmission elec... | Ordering Structure; Growth Temprature; Growth Rate | 1994 |
| 31 |
 |
Tiwari, Ashutosh | Copper diffusion characteristics in single crystal and polycrystalline TaN | TaN has become a very promising diffusion barrier material for Cu interconnections, due to the high thermal stability requirement and thickness limitation for next generation ULSI devices. TaN has a variety of phases and Cu diffusion characteristics vary with different phases and microstructures. We... | Diffusion barriers; Copper diffusion; Tantalum nitride | 2003 |
| 32 |
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Tiwari, Ashutosh | Copper diffusion characteristics in single-crystal and polycrystalline TaN | We have investigated the diffusivity of copper in single-crystal (NaCl-structured) and polycrystalline TaN thin films grown by pulsed-laser deposition. Polycrystalline TaN films were grown directly on Si(100), while single-crystal films were grown with TiN buffer layers. Both poly- and single-crysta... | Diffusion barriers; Copper diffusion; Tantalum nitride | 2002 |
| 33 |
 |
Stringfellow, Gerald B. | Correlation between surface structure and ordering in GaInP | Ga and In atoms in Ga0.52In0.48P layers spontaneously segregate to form alternating In- and Ga-rich {111} monolayers during organometallic vapor phase epitaxial (OMVPE) growth on (001) oriented GaAs substrates, thus forming the CuPt ordered structure. This ordering phenomenon is believed to be drive... | Transformations; Absorbtion spectra; Surface Properties | 1996 |
| 34 |
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Liu, Feng | Coulomb sink: a novel Coulomb effect on coarsening of metal nanoclusters on semiconductor surfaces | We propose the concept of a ‘‘Coulomb sink'' to elucidate the effect of Coulomb charging on coarsening of metal mesas grown on semiconductor surfaces.We show that a charged mesa, due to its reduced chemical potential, acts as a Coulomb sink and grows at the expense of neighboring neutral mesas. ... | Coulomb sink; Coulomb effect; Metal nanoclusters; Semiconductor surface; Pb mesas | 2004-09 |
| 35 |
 |
Liu, Feng | Creation of "quantum platelets" via strain-controlled self-organization at steps | We demonstrate, by both theory and experiment, the strain-induced self-organized formation of "quantum platelets," monolayer-thick islands of finite dimensions. They form at the early stage of heteroepitaxial growth on a substrate with regularly spaced steps, and align along the steps. In the direc... | Quantum platelets; Strain-controlled self-organization; Monolayer-thick islands; Heteroepitaxial growth | 2000-12 |
| 36 |
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Liu, Feng | Critical epinucleation on reconstructured surfaces and first-principle calculation of homonucleation on Si(100) | We introduce the concept of ‘‘critical epinucleation'' to distinguish nucleation on surfaces with and without reconstruction. On a reconstructed surface, the critical classical nucleus is stable against dissociation, but may not yet break the underlying surface reconstruction. Consequently, ther... | Critical epinucleation; First-principle calculation; Homonucleation; Si(100); Islands | 2005-09 |
| 37 |
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Tiwari, Ashutosh | CuBO2: a p-type transparent oxide | The authors report the synthesis of CuBO2, a p-type transparent oxide belonging to Cu-delafossite family. High quality thin films of CuBO2 were deposited on c-plane sapphire substrates by pulsed laser deposition technique. Detailed structural, optical, and electrical characterizations on these films... | Transparent conducting oxides; Delafossite series; CuBO2 | 2007 |
| 38 |
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Stringfellow, Gerald B. | Deep electron traps in organometallic vapor phase grown AlGaAs | Deep electron traps have been studied by means of deep level transient spectrosocopy in type nominally undoped and interntionally te doped Al Ga As epitaxial layers which were grown by vapor phase epitaxy from organometallic compounds (OMVPE). Three main deep electron levels are present in undoped m... | Vapor phase epitaxy; Shallow impurity identity; Optoelectronic device performance | 1980 |
| 39 |
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Scarpulla, Michael | Detection of ZnS phases in CZTS thin-films by EXAFS | Copper zinc tin sulfide (CZTS) is a promising Earthabundant thin-film solar cell material; it has an appropriate band gap of ~1.45 eV and a high absorption coefficient. The most efficient CZTS cells tend to be slightly Zn-rich and Cu-poor. However, growing Zn-rich CZTS films can sometimes result in ... | | 2011-01-01 |
| 40 |
 |
Liu, Feng | Determination of the Ehrlich-Schwoebel barrier in epitaxial growth of thin films | We 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; Adatoms | 2006-11 |
| 41 |
 |
Scarpulla, Michael | Determination of the infrared complex magnetoconductivity tensor in itinerant ferromagnets from Faraday and Kerr measurements | We present measurement and analysis techniques that allow the complete complex magnetoconductivity tensor to be determined from midinfrared (11-1.6 μm; 100-800 meV) measurements of the complex Faraday (θF) and Kerr (θK) angles. Since this approach involves measurement of the geometry (orientati... | Magnetoconductivity tensor; Ferromagnets | 2007-06 |
| 42 |
 |
Liu, Feng | Determining the adsorptive and catalytic properties of strained metal surfaces using adsorption-induced stress | We demonstrate a model for determining the adsorptive and catalytic properties of strained metal surfaces based on linear elastic theory, using first-principles calculations of CO adsorption on Au and K surfaces and CO dissociation on Ru surface. The model involves a single calculation of the adsorp... | Strained metal surfaces; Adsorption-induced stress; Adsorptive properties; Catalytic properties | 2004 |
| 43 |
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Scarpulla, Michael | Diluted II-VI oxide semiconductors with multiple band gaps | We report the realization of a new mult-band-gap semiconductor. Zn1-yMnyOxTe1-x alloys have been synthesized using the combination of oxygen ion implantation and pulsed laser melting. Incorporation of small quantities of isovalent oxygen leads to the formation of a narrow, oxygen-derived band of ... | Highly mismatched alloys; Zinc telluride | 2003-12 |
| 44 |
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Stringfellow, Gerald B. | Dislocations in GaAs17-xPx | Dislocations, their origins, and their effects on photoluminescence efficiency have been studied in GaAs1-xPx single crystals grown by vapor phase epitaxy. Dislocations were observed using etch pit, optical-transmission microscopy, and x-ray topography techniques. Two types of dislocations are grown... | Photoluminescence efficiency; Growth mechanism; Optical transmission microscopy | 1969 |
| 45 |
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Stringfellow, Gerald B. | Doping studies of Ga0.5In0.5P organometallic vapor-phase epitaxy | Presents doping studies of gallium[sub0.5] indium[sub0.5] phosphorus organometallic vapor-phase epitaxy. Distribution coefficient of indium; Description of growth conditions; Case of poor growth morphology for gallium[sub0.5] indium[sub0.5] phosphorus. | Phosphorus; Gallium; Doping | 1986 |
| 46 |
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Scarpulla, Michael | Effect of film thickness on the incorporation of Mn interstitials in Ga1-xMnxAs | We have investigated the effect of film thickness on the distribution of Mn atoms at various lattice sites in Ga1−xMnxAs thin films. We find that the growth surface acts as a sink facilitating the outdiffusion of Mn interstitials sMnId, and thus reducing its concentration in the film. The outdiffu... | Interstitials; Gallium arsenide | 2005 |
| 47 |
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Stringfellow, Gerald B. | Effect of growth rate on step structure and ordering in GaInP | CuPt ordering is widely observed in GaInP epitaxial layers grown by organometallic vapor phase epitaxy. The formation of this spontaneously ordered structure during epitaxial growth is intimately related to the atomic-scale physical processes occurring on the surface, specifically surface reconst... | Atomic force microscopy; Organometallic vapor phase; Crystallographic plane | 1997 |
| 48 |
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Stringfellow, Gerald B. | Effect of oxygen incorporation in semi-insulating (AlxGa1-x)yIn1-yP | Discusses 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 oxygen | 1992 |
| 49 |
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Liu, Feng | Effect of size and dimensionality on the magnetic moment of transition metals | The effect of size and dimensionality on the magnetic moments of Fe, Co, and Ni have been studied theoretically by confining the atoms t o various structural forms such as chains,surfaces, and thin films. The size of these systems is controlled by limiting t h e number of atoms. A new first-princip... | Magnetic moment; Dimensionality; Size effects; Fe; Co; Ni | 1990 |
| 50 |
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Stringfellow, Gerald B. | Effect of step structure on ordering in GaInP | Examines the effect of step structure on ordering in gallium indium phosphite (GaInP) using atomic force microscopy. Coverage of the surface by islands several monolayers in height with elongated direction; Formation of the edges of the islands; Role of the observations in explaining the nature of t... | Gallium indium phosphite (GaInP); Twin boundaries | 1995-11-12 |
| 51 |
 |
Stringfellow, Gerald B. | Effect of surfactant Sb on carrier lifetime in GaInP epilayers | Samples of Ga0.52In0.48P grown on (001) GaAs with small amounts of surfactant Sb were investigated using time-resolved photoluminescence. All samples show a luminescence that may be fit to a two-stage exponential decay with a fast and a slow lifetime. For growth without Sb (Sb/III(v)(0), the sample ... | Semiconductor ternary alloys; Epitaxial layer; Microstructures | 2002-01-01 |
| 52 |
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Stringfellow, Gerald B.; Rieth, Loren W. | Effects of Br and Cl on organometallic vapor phase epitaxial growth and ordering in GaInP | CuPt ordering in GaInP has significant effects on the electrical and optical properties. In fact, band gap reductions as large as 160 meV are potentially useful for devices. Thus, control of ordering is important. This has led to the investigation of surfactants that affect the surface processes d... | Band gap reductions; Surfactants; Surface processes | 2004 |
| 53 |
 |
Liu, Feng | Effects of Li doping on H-diffusion in MgH2: A first-principles study | The 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 |
| 54 |
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Scarpulla, Michael | Effects of pressure on the band structure of highly mismatched Zn1-yMnyOxTe1-x alloys | We report photomodulation spectroscopy measurements of the pressure dependence of the optical transition in Zn12yMnyOxTe1-x alloys that is associated with the lowest Ѓ conduction band (termed E2 subband). The pressure-induced energy shift of the E2 transition is nonlinear and much weaker as compare... | Highly mismatched alloys; Zinc telluride; Anticrossing | 2004 |
| 55 |
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Scarpulla, Michael | Effects of sodium on electrical properties in Cu2ZnSnS4 single crystal | We have studied the effect of sodium on the electrical properties of Cu2ZnSnS4 (CZTS) single crystal by using temperature dependence of Hall effect measurement. The sodium substitution on the cation site in CZTS is observed from the increasing of unit-cell size by powder X-ray diffraction. Sodium in... | | 2014-01-01 |
| 56 |
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Stringfellow, Gerald B. | Effects of substrate misorientation and growth rate on ordering in GaInP | Epitaxial layers of Ga,Tn,_,P with 1=0.52 have been grown by-organometallic vapor-phase apitaxy on GaAs substrates misoriented from the (001) plane in the [ 1 IO] direction by angles 6,) of O", 3", 6", and 9". For each substrate orientation growth rates rg of 1, 2, and 4 pm/h have been used. The ... | Transmission electron diffraction; Dark-field imaging; Photoluminescence | 1994 |
| 57 |
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Stringfellow, Gerald B. | Effects of surfactants Sb and Bi on the incorporation of zinc and carbon in III/V materials grown by organometallic vapor-phase epitaxy | The incorporation of both dopants and background impurities during the organometallic vapor phase epitaxial _x0002_OMVPE_x0003_ growth of GaAs, GaInP, and GaP has been significantly altered by the use of the surfactants Sb and Bi. Sb and Bi are isoelectronic with the group V host elements, and so ... | Physical and chemical processes; Surfactants isoelectronic; Electrochemical C-V profilometry | 2006 |
| 58 |
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Stringfellow, Gerald B. | Effects of V/III ratio on ordering and antiphase boundaries in GaInP layers | Transmission electron microscope (TEM) and transmission electron diffraction (TED) studies have been performed to investigate the effects of V/III ratio on ordering and antiphase boundaries (APBs) in organometallic vapor phase epitaxial Ga0.5In0.5P layers grown onto (001) GaAs vicinal substrates ... | Antiphase boundaries; APB; Heterostructures; Organometallics | 1997 |
| 59 |
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Stringfellow, Gerald B. | Effects of V/III ratio on ordering in GaInP: atomic scale mechanisms | Ga0.5In0.5P layers have been grown by organometallic vapor-phase epitaxy using various values of input V/III ratio for two phosphorus precursors, phosphine, the conventional precursor, and tertiarybutylphosphine (TBP), a newly developed, less-hazardous precursor. For growth on nominally (001) GaAs s... | Photoabsorption spectroscopy; Transmission electron diffraction; Phosphorus precursor | 1996-05-01 |
| 60 |
 |
Stringfellow, Gerald B. | Electrical properties of nitrogen doped GaP | The electrical properties namely, electron concentration and mobility, have been investigated in the temperature range from 53 to 400 K for undoped and nitrogen-doped VPE GaP. | Electron concentration; Ionization energy; Electron mobility | 1975 |
| 61 |
 |
Tiwari, Ashutosh | Electrical properties of transparent and conducting Ga doped ZnO | In this paper, we report on the metal-semiconductor transition behavior observed in transparent and conducting ZnO:Ga films grown by pulsed-laser deposition. The electrical resistivity measurements were carried out on ZnO films with varying Ga concentration in the temperature range of 14 to 300 K. ... | Transparent conducting oxides; ZnO; Gallium; Metallic conductivity | 2006 |
| 62 |
 |
Scarpulla, Michael | Electrical transport and ferromagnetism in Ga1−xMnxAs synthesized by ion implantation and pulsed-laser melting | We present a detailed investigation of the magnetic and magnetotransport properties of thin films of ferromagnetic Ga1−xMnxAs synthesized using ion implantation and pulsed-laser melting (II-PLM). The field and temperature-dependent magnetization, magnetic anisotropy, temperature-dependent resist... | GaMnAs; Gallium arsenide | 2008 |
| 63 |
 |
Tiwari, Ashutosh | Electrical transport in ultrathin NdNiO3 films | Electrical transport properties in ultrathin NdNiO3 films grown on single crystal LaAlO3 (001) substrate were characterized. Films with thicknesses ranging from 0.6 nm to 12 nm were grown using a pulsed laser technique. Four probe resistivity as a function of temperature measurements indicated a str... | | 2012-01-01 |
| 64 |
 |
Tiwari, Ashutosh | Electrical transport in ZnO1-δ films: transition from band-gap insulator to Anderson localized insulator | We have thoroughly investigated the effect of oxygen nonstoichiometry on the electrical transport characteristics of ZnO1−δ films. These films were grown on optical grade quartz substrates by using a pulsed laser deposition technique. In order to alter the amount of oxygen nonstoichiometry (δ), ... | Anderson localized insulators | 2004 |
| 65 |
 |
Liu, Feng | Electrochemical measurements on cells, I: Simulation of potential distribution with an embedded probe | Measurements 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 |
| 66 |
 |
Scarpulla, Michael | Electron backscatter diffraction and photoluminescence of sputtered CdTe thin films | Electron backscatter diffraction (EBSD) has been used to characterize the grain size, grain boundary structure, and texture of sputtered CdTe at varying deposition pressures before and after CdCl2 treatment in order to correlate performance with film microstructure. It is known that twin boundaries ... | | 2011-01-01 |
| 67 |
 |
Stringfellow, Gerald B. | Electron mobility in AlxGa1-xAs | he electron mobility in AlxGa1-xAs grown by several techniques has been studied to determine whether VPE layers are more highly compensated than comparable LPE layers. The techniques used to grow layers included (1) organometallic VPE using Al(CH3)3, AsH3, and Ga(C2H5)3 or Ga(CH3)3, (2) ''hybrid'' o... | Alloys; Organometallics | 1979-06 |
| 68 |
 |
Stringfellow, Gerald B. | Electron mobility in compensated GaAs and AlGaAs | The dependence of electron mobility on temperature in GaAs and Al Ga As indicates that for cimpensated material a term having causes a significant reduction in the mobility measured at high temperatures. The magnitude of the term in mobility, denoted is found to be linearly proportional to the compe... | Unspecified mobility; Reduced mobility; Space charge regions | 1980 |
| 69 |
 |
Tiwari, Ashutosh | Electron tunneling experiments on La0.7A0.3MnO3 (A=Ca, Sr, Ba) | Tunneling conductance measurements of the electronic density of states of perovskite manganates, La0.7A0.3MnO3 are reported. Tunneling data of all the samples show a zero-bias anomaly with a minimum in the density of states at the Fermi level. This behavior is interpreted as arising from strong elec... | Perovskite manganates; Tunneling conductance | 1999-10 |
| 70 |
 |
Liu, Feng | Electronic and elastic properties of edge dislocations in Si | Ab initio, tight-binding, and classical calculations have been done for (a/2)( 110) edge dislocation dipoles in Si at separations of 7.5-22.9 A in unit cells comprising 32-288 atoms. These calculations show states associated with the cores relatively deep in the band gap (~ 0.2 eV) despite the abse... | Edge dislocations | 1995-06 |
| 71 |
 |
Liu, Feng | Electronic strengthening of graphene by charge doping | Graphene is known as the strongest 2D material in nature, yet we show that moderate charge doping of either electrons or holes can further enhance its ideal strength by up to 17%, based on first-principles calculations. This unusual electronic enhancement, versus conventional structural enhancement,... | | 2012-01-01 |
| 72 |
 |
Scarpulla, Michael | Enhanced absorption in optically thin solar cells by scattering from embedded dielectric nanoparticles | Abstract: We present a concept for improving the efficiency of thin-film solar cells via scattering from dielectric particles. The particles are embedded directly within the semiconductor absorber material with sizes on the order of one wavelength. Importantly, this geometry is fully compatible wit... | | 2010 |
| 73 |
 |
Liu, Feng | Enhanced growth instability of a strained film on wavy substrate | We demonstrate that the growth of a strained film is inherently less stable on a wavy substrate than on a flat substrate. For small surface undulation, the lowest strain energy state is for the film surface to adopt the same wavelength as the substrate surface in an antiphase configuration at the ea... | Growth instability; Strained film; Wavy substrate; Strain induced self-assembly | 2008 |
| 74 |
 |
Scarpulla, Michael | Enhanced light absorption in thin-film silicon solar cells by scattering from Embedded Dielectric Nanoparticles | We investigate the light-trapping effects of dielectric nanoparticles embedded within the active semiconductor layer of a thin-film solar cell. The baseline model consists of a 1.0 μm slab of crystalline silicon on an aluminum back contact topped with a 75 nm Si3N4 anti-reflective coating. Using fi... | | 2011-01-01 |
| 75 |
 |
Scarpulla, Michael | Enhanced nitrogen incorporation by pulsed laser annealing of GaNxAs1-x formed by N ion implantation | We demonstrate that pulsed laser annealing followed by rapid thermal annealing greatly enhances incorporation of substitutional N in N1-implanted GaAs. Films implanted to 1.8% N exhibit a fundamental band gap of 1.26 eV (a band gap reduction of 160 meV), corresponding to an N activation efficiency ... | Highly mismatched alloys; Gallium arsenide | 2002 |
| 76 |
 |
Tiwari, Ashutosh | Epitaxial growth and properties of MoOx(2 | We report the growth of epitaxial molybdenum oxide (MoOx,2<x<2.75) films on c plane of sapphire substrate using pulsed laser deposition in oxygen environment. The structure was characterized using x-ray diffraction, high resolution transmission electron microscopy and x-ray photoelectron spectroscop... | Epitaxy; MoO | 2005 |
| 77 |
 |
Tiwari, Ashutosh | Epitaxial growth and properties of Zn1-xVxO diluted magnetic semiconductor thin films | Here we report systematic studies on the epitaxial growth and properties of Zn1−xVxO[x=0.001-0.2] thin films deposited onto sapphire c-plane single crystals. The thin films were deposited using pulsed laser deposition technique and were found to be epitaxial in nature. X-ray diffraction and high ... | ZnO; Vanadium | 2005 |
| 78 |
 |
Liu, Feng | Epitaxial growth of large-gap quantum spin Hall insulator on semiconductor surface : The substrate orbital filtering effect | Formation of topological quantum phase on conventional semiconductor surface is of both scientific and technological interest. Here, we demonstrate epitaxial growth of 2D topological insulator, i.e. quantum spin Hall (QSH) state, on Si(111) surface with a large energy gap, based on first-principles ... | | 2014-01-01 |
| 79 |
 |
Tiwari, Ashutosh | Epitaxial growth of magnetic nickel nanodots by pulsed laser deposition | Epitaxial nickel magnetic nanodots were obtained by pulsed laser deposition (PLD) technique on Si (100) substrate using epitaxial TiN film as the template. Characterization methods include: high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) Z-... | Nanodots; TiN; Nickel | 2003 |
| 80 |
 |
Tiwari, Ashutosh | Epitaxial growth of TaN films on Si(100) and Si(111) using a TiN buffer layer | We have deposited high-quality epitaxial B1 NaCl-structured TaN films on Si(100) and Si(111) substrates with TiN as the buffer layer, using pulsed laser deposition. Our method exploits the concept of lattice-matching epitaxy between TiN and TaN and domain-matching epitaxy between TiN and silicon. X... | Diffusion barriers; Buffer layers; Tantalum nitride; Silicon substrate | 2002 |
| 81 |
 |
Tiwari, Ashutosh | Epitaxial growth of ZnO films on Si(111) | In this paper, we report the growth of ZnO films on silicon substrates using a pulsed laser deposition technique. These films were deposited on Si(111) directly as well as by using thin buffer layers of AlN and GaN. All the films were found to have c-axis-preferred orientation aligned with normal to... | Buffer layers; Aluminum nitride; Silicon substrate; Biaxial strain | 2002 |
| 82 |
 |
Bedrov, Dmitro; Smith, Grant D. | Equilibrium sampling of self-associating polymer solutions: a parallel selective tempering approach | We present a novel simulation algorithm based on tempering a fraction of relaxation-limiting interactions to accelerate the process of obtaining uncorrelated equilibrium configurations of self-associating polymer solutions. This approach consists of tempering (turning off) the attractive interactio... | Equilibrium sampling; Self-associating systems; Parallel selective tempering | 2005 |
| 83 |
 |
Liu, Feng | Equilibrium shape of two-dimensional islands under stress | We show that the equilibrium shape anisotropy of two-dimensional islands in heteroepitaxial growth depends on island size, a consequence of the presence of strain. Even in homoepitaxy, in which the island shape has conventionally been equated with the ratio of step energies, a substrate surface str... | Two-dimensional islands; Equilibrium shape; Heteroepitaxial growth; Homoepitaxy | 2000-08 |
| 84 |
 |
Scarpulla, Michael | Exact field solution to guided wave progagation in lossy thin films | Wave guidance is an important aspect of light trapping in thin film photovoltaics making it important to properly model the effects of loss on the field profiles. This paper derives the full-field solution for electromagnetic wave propagation in a symmetric dielectric slab with finite absorption. ... | | 2011 |
| 85 |
 |
Liu, Feng | Exceptional optoelectronic properties of hydrogenated bilayer silicene | Silicon is arguably the best electronic material, but it is not a good optoelectronic material. By employing first-principles calculations and the cluster-expansion approach, we discover that hydrogenated bilayer silicene (BS) shows promising potential as a new kind of optoelectronic material. Most ... | | 2014-01-01 |
| 86 |
 |
Liu, Feng | Exotic electronic states in the world of flat bands: from theory to material | It has long been noticed that special lattices contain single-electron at bands (FB) without any dispersion. Since the kinetic energy of electrons is quenched in the FB, this highly degenerate energy level becomes an ideal platform to achieve strongly correlated electronic states, such as magnetism,... | | 2014-01-01 |
| 87 |
 |
Tiwari, Ashutosh | Experiments along coexistence near tricriticality in 3He-4He mixtures | The tricritical point in the phase diagram of 3He-4He mixtures offers unique opportunities to test our understanding of critical phenomena. Because D = 3 is the marginal spatial dimension for tricriticality, the associated critical exponents are exact integer fractions. In addition, one expects to f... | Tricriticality; Tricritical point; 3He-4He mixtures | 2000 |
| 88 |
 |
Bedrov, Dmitro; Smith, Grant D. | Exploration of conformational phase space in polymer melts: a comparison of parallel tempering and conventional molecular dynamics simulations | Parallel tempering molecular dynamics simulations have been performed for 1,4-polybutadiene polymer melts in the 323 K-473 K temperature domain at atmospheric pressure. The parallel tempering approach provides a vast improvement in the equilibration and sampling of conformational phase space for ... | Polymer melts; 1,4-polybutadiene; Conformational phase space; Parallel tempering | 2001 |
| 89 |
 |
Liu, Feng | Fabricating artificial nanowells with tunable size and shape by using scanning tunneling microscopy | The authors report a method of precisely fabricating the large-scale nanocrystals with well-defined shape and size. The (111) oriented Pb islands deposited on Si(111)-7x7 substrate were investigated with a manipulation technique based on scanning tunneling microscopy. By applying a series of voltage... | Artificial nanowells | 2006 |
| 90 |
 |
Tiwari, Ashutosh | Fabrication and characterization of Li7La3Zr 2O12 thin films for lithium ion battery | Thin films of Li7La3Zr2O12 were deposited on SrTiO3 (100) and Sapphire (0001) substrates at room-temperature using a pulsed-laser-deposition technique. Detailed structural, compositional, optical, and electrochemical characterizations of the films were performed. The films deposited at room-temperat... | | 2012-01-01 |
| 91 |
 |
Scarpulla, Michael | Fabrication of GaNxAs1-x quantum structures by focused ion beam patterning | A novel approach to the fabrication of GaNxAs1-x quantum dots and wires via ion beam patterning is presented. Photomodulated reflectance spectra confirm that N can be released from the As sublattice of an MBE-grown GaNxAs1-x film by amorphization through ion implantation followed by regrowth upon r... | Gallium arsenide; Quantum dots; Quantum wires; Thermal annealing | 2005 |
| 92 |
 |
Scarpulla, Michael | Ferromagnetic Ga1-xMnxAs produced by ion implantation and pulsed-laser melting | We demonstrate the formation of ferromagnetic Ga1-xMnxAs films by Mn ion implantation into GaAs followed by pulsed-laser melting. Irradiation with a single excimer laser pulse results in the epitaxial regrowth of the implanted layer with Mn substitutional fraction up to 80% and effective Curie tempe... | Gallium arsenide; Ferromagnetic semiconductors; Remanent magnetization | 2003 |
| 93 |
 |
Scarpulla, Michael | Ferromagnetic resonance investigation of magnetic anisotropy in Ga1-xMnxAs synthesized by ion implantation and pulsed laser melting | A systematic investigation of ferromagnetic resonance (FMR) was carried out on Ga1−xMnxAs layers synthesized by Mn ion implantation into GaAs followed by pulsed laser melting. Angular and temperature dependences of FMR were measured on layers prepared on GaAs (001), (110), and (311) surfaces. The ... | Magnetic anisotropy; Ga1−xMnxAs; Gallium manganese arsenide | 2009-12 |
| 94 |
 |
Tiwari, Ashutosh | Ferromagnetism in Co doped CeO2: observation of giant magnetic moment with a high Curie temperature | We report room temperature ferromagnetism in single crystal Ce1−xCoxO2−δ (x≤0.05) films deposited on a LaAlO3(001) substrate. Films were grown by a pulsed laser deposition technique and were thoroughly characterized using x-ray diffraction, high-resolution transmission electron microscopy cou... | CeO2; Cobalt | 2006 |
| 95 |
 |
Tiwari, Ashutosh | Ferromagnetism in Cu-doped ZnO films: role of charge carriers | We report the observation of room temperature ferromagnetism in Cu-doped (5%) ZnO films grown on c-plane sapphire substrates. Films were prepared by pulsed laser deposition technique and were thoroughly characterized using several state-of-the-art characterization techniques. Hall measurements sho... | Charge carriers | 2008 |
| 96 |
 |
Scarpulla, Michael | Ferromagnetism in Ga1-xMnxP: evidence for inter-Mn exchange mediated by localized holes within a detached impurity band | We report an energy gap for hole photoexcitation in ferromagnetic Ga1-xMnxP that is tunable by Mn concentration (x ≤ 0:06) and by compensation with Te donors. For x ~ 0:06, electrical transport is dominated by excitation across this gap above the Curie temperature (TC) of 60 K and by thermally a... | Gallium Phosphide; Ferromagnetism; Mn impurity band | 2005-11 |
| 97 |
 |
Liu, Feng | First-principles calculation of interaction between interstitial O and As dopant in heavily As-doped Si | We investigate the interaction between interstitial oxygen (Oi) and As dopant in heavily As-doped Si using first-principles total-energy calculations. The interaction between Oi and As (substitutional) is found to be short ranged. The most stable configuration is with As and Oi as second nearest nei... | First-principles calculation; Interstitial oxygen; As dopant; As-doped Si; Oxygen diffusion; Oi | 2007 |
| 98 |
 |
Liu, Feng | First-principles studies on structural properties of β-cristobalite | The structure of β-cristobalite has been studied through a first-principles total-energy minimization in the local-density approximation using a Car-Parrinello-type algorithm combined with the Vanderbilt ultrasoft pseudopotential scheme. It was found that the hypothetical ordered structure propose... | First-principles; Car-Parrinello-type algorithm | 1993-05 |
| 99 |
 |
Liu, Feng | First-principles study of crystalline silica | We have investigated the structural properties of five different crystalline forms of Si02 using a first-principles approach. An ultrasoft Vanderbilt pseudopotential is generated for oxygen which enables us to use a small plane-wave cutoff of 25 Ry. The relative stability, the equation of state, an... | First-principles; Crystalline silica; Ultrasoft Vanderbilt pseudopotential | 1994-05 |
| 100 |
 |
Liu, Feng | First-principles study of electronic properties of biaxially strained silicon: effects on charge carrier mobility | Using first-principles method, we calculate the electronic band structure of biaxially strained silicon, from which we analyze the change in electron and hole effective mass as a function of strain and determine the mobility of electrons and holes in the biaxially strained silicon based on Boltzmann... | Biaxially strained silicon; Boltzmann transport theory | 2008-12 |
| 101 |
 |
Liu, Feng | First-principles study of impurity segregation in edge dislocations in Si | Using ab initio calculations, the segregation of As, Ga, and Ge atoms in the core regions of perfect edge dislocations in Si is examined. When all nearest neighbors of an impurity are Si atoms, As favors the core site at maximum compression and has a segregation energy of 0.25 eV/atom. Ga and Ge im... | First-principles; Impurity segregation; Edge dislocations | 2000-01 |
| 102 |
 |
Liu, Feng | First-principles study of strain stabilization of Ge(105) facet on Si(001) | Using the first-principles total energy method, we calculate surface energies, surface stresses, and their strain dependence of the Ge-covered Si (001) and (105) surfaces. The surface energy of the Si(105) surface is shown to be higher than that of Si(001), but it can be reduced by the Ge deposition... | First-principles calculation; Strain stabilization; Ge(105); Si(001); Strained thin films; Epitaxial growth | 2005-09 |
| 103 |
 |
Tiwari, Ashutosh | Formation of self-assembled epitaxial nickel nanostructures | Highly orientated nickel magnetic nanoparticles were obtained by pulsed laser deposition technique on silicon (100) substrate using epitaxial titanium nitride film as the template. These nanoparticles have been characterized by conventional and high-resolution transmission electron microscopy, scann... | TiN; Nickel | 2003 |
| 104 |
 |
Scarpulla, Michael | Ga1-xMnxP synthesized by ion implantation and pulsed-laser melting | The synthesis of single-crystalline epitaxial thin films of the carrier-mediated ferromagnetic phase of Ga1-xMnxP and Ga1-xMnxP-based quaternary alloys using ion implantation and pulsed-laser melting (II-PLM) has allowed for the exploration of the effect of anion substitution on ferromagnetism in Ga... | | 2008 |
| 105 |
 |
Stringfellow, Gerald B. | GaInAsSb metastable alloys grown by organometallic vapor phase epitaxy | Ga1-xlnx As1-ySby alloys have been grown by organometallic vapor phase epitaxy using trimethyl compounds of Ga, In, As, and Sb(TMGa, TMIn, TMAs, and TMSb) plus AsH3 in an atmospheric pressure, horizontal, infrared heated reactor. For the first time, alloys near the center of the region of solid immi... | Organometallic; Alloys; Vapor phase epitaxy | 1986 |
| 106 |
 |
Tiwari, Ashutosh | Garnet-type Li7La3Zr2O12 electrolyte prepared by a solution-based technique for lithium ion battery | High 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 |
| 107 |
 |
Liu, Feng | Geometric constant defining shape transitions of carbon nanotubes under pressure | We 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; Pressure | 2004-03 |
| 108 |
 |
Liu, Feng | Giant room-temperature spin caloritronics in spin-semiconducting graphene nanoribbons | Spin caloritronics refers to generating spin current by thermal gradient. Here we report a theoretical study demonstrating giant spin caloritronic effects in a new class of materials, called spin semiconductors, which are characterized with a "spin gap," the energy gap between spin-up and -down chan... | | 2014-01-01 |
| 109 |
 |
Scarpulla, Michael | Grain size and texture of Cu2ZnSnS4 thin films synthesized by co-sputtering binary sulfides and annealing: effects of processing conditions and sodium | We 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 |
| 110 |
 |
Tiwari, Ashutosh | Growth and characterization of TaN/TiN superlattice structures | Epitaxial B1 NaCl-structured TaN(3 nm)/TiN(2 nm) superlattice structures were grown on Si(100) substrates with a TiN buffer layer, using pulsed-laser deposition. A special target assembly was used to manipulate the thickness of each layer. X-ray diffraction, transmission electron microscopy, and ... | Diffusion barriers; Copper diffusion; Tantalum nitride | 2003 |
| 111 |
 |
Tiwari, Ashutosh | Growth of epitaxial NdNiO3 and integration with Si(100) | We have grown epitaxial NdNiO3 films on Si(100) substrate under ambient oxygen pressure using a pulsed-laser deposition method. The integration of NdNiO3 with Si(100) was accomplished by lattice-matching epitaxy of MgO and SrTiO3 and domain matching epitaxy of TiN on Si(100). During domain matching... | NdNiO3; SrTiO3; Silicon substrate | 2002 |
| 112 |
 |
Tiwari, Ashutosh | Growth of epitaxial ZnO films on Si(111) | Epitaxial ZnO films have been grown on Si(l 11) substrates by employing a A1N buffer layer during a pulsed laser-deposition process. The epitaxial structure of A1N on Si(l 11) substrate provides a template for ZnO growth. The resultant films are evaluated by transmission electron microscopy, x-ray ... | Buffer layers; Aluminum nitride; Silicon substrate | 2002 |
| 113 |
 |
Scarpulla, Michael | Heat flow model for pulsed laser melting and rapid solidification of ion implanted GaAs | In order to further understand the pulsed-laser melting (PLM) of Mn and N implanted GaAs, which we have used to synthesize thin films of the ferromagnetic semiconductor Ga1−xMnxAs and the highly mismatched alloy GaNxAs1−x, we have simulated PLM of amorphous (a-) and crystalline (c-) GaAs. We pre... | | 2010 |
| 114 |
 |
Stringfellow, Gerald B.; Shurtleff, James Kevin | Heterostructures in GaInP grown using a change in Te doping | In organometallic vapor phase epitaxy, changes in growth conditions can be used to modulate the extent of CuPt ordering and, hence, the band gap energy of GaInP. One method is to add Te during growth. An increase in the band gap energy of 0.1 eV due to a decrease in ordering has been obtained by ... | Heterostructures; Alloys | 2000 |
| 115 |
 |
Stringfellow, Gerald B. | Heterostructures in GaInP grown using a change in V/III ratio | A natural monolayer 111% superlattice -- the CuPt ordered structure -- is formed spontaneously during organometallic vapor phase epitaxial OMVPE growth of Ga0.52In0.48P. The extent of this ordering process is found to be a strong function of the input partial pressure of the phosphorus precursor dur... | Superlattices; Alloys; Atomic ordering; Heterostructures | 1997-02-24 |
| 116 |
 |
Liu, Feng | Hydrogen induced Si surface segregation on Ge-covered Si(001) | Using Fourier transform infrared-attenuated total reflectance spectroscopy in conjunction with hydrogen adsorption to probe surface layer composition, we observe a reversible place exchange between Ge and Si on Ge-covered Si(001) when the surface is dosed with atomic H at elevated temperatures. F... | Si surface segregation; Ge-covered; Si(001) | 1998-10 |
| 117 |
 |
Scarpulla, Michael | The importance of Se partial pressure in the laser annealing of CuInSe2 electrodeposited precursors | One 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 |
| 118 |
 |
Liu, Feng | Impurity mediated absorption continuum in single-walled carbon nanotubes | The authors demonstrate that in single-walled carbon nanotubes, a weak impurity potential can lead to a strong above-gap absorption continuum. The total absorption is enhanced due to the intraband and indirect transitions, as well as plasmon excitations, which are forbidden in perfect nanotubes. Suc... | Carbon nanotubes; SWNT; Defects; Impurities; Above-gap; Absorption continuum | 2007 |
| 119 |
 |
Stringfellow, Gerald B. | InAsSbBi alloys grown by organometallic vapor-phase epitaxy | Provides information on a study on the growth of InAsSbBi alloys by organometallic vapor-phase epitaxy. Experiment; Results and discussion; Conclusion. | Alloys; Epitaxy; Organometallic Compounds | 1994 |
| 120 |
 |
Liu, Feng | Influence of quantum size effects on Pb island growth and diffusion barrier oscillations | Quantum size effects are successfully exploited in manipulating the growth of (111) oriented Pb islands on Si(111) substrate with a scanning tunneling microscope. The growth dynamics and morphology displayed can be well controlled through the quantum size effects defined by the island thicknesses ... | Quantum size effects; QSE; Pb island; Diffusion barrier oscillations | 2006-08 |
| 121 |
 |
Stringfellow, Gerald B. | Influence of Sb, Bi, Tl, and B on the incorporation of N in GaAs | GaAs:N is an interesting material for many devices due to its unique compositional variation of band gap. Small amounts of N lead to a strong decrease in band gap energy as well as lattice constant. The further addition of In or Sb leads to quaternary alloys with band gap energies below 1.4 eV latti... | Antimony; Gallium Arsenide; Nitrogen | 2002 |
| 122 |
 |
Stringfellow, Gerald B. | Influence of tellurium doping on step bunching of GaAs (001) vicinal surfaces grown by organometallic vapor phase epitaxy | Atomic force microscopy has been used to investigate the influence of controlled tellurium Te incorporation on the step structure of GaAs grown by organometallic vapor phase epitaxy on vicinal 001 surfaces. Te doping, using the precursor diethyltelluride, is found to markedly decrease the surface r... | Epitaxial growth; Misorientation; Organometallic vapor phase epitaxy | 1998 |
| 123 |
 |
Bedrov, Dmitro; Smith, Grant D. | Integral equation theory for polymer solutions: explicit inclusion of the solvent molecules | Self-consistent Polymer Reference Interaction Site Model (PRISM) calculations and molecular dynamics (MD) simulations were performed on athermal solutions of linear polymers. Unlike most previous treatments of polymer solutions, we explicitly included the solvent molecules. The polymers were mode... | Solvent molecules; Polymer Reference Interaction Site Model; PRISM; Spinodal curve; Intramolecular dimensions; Intermolecular packing; Phase behavior | 2001 |
| 124 |
 |
Chaudhuri, Reaz A. | Interlaminar shear stresses around an internal part-through hole in a stretched laminated composite plate | The equilibrium/compatibility method, which is a semi-analytical post-processing method, is employed for computation of hitherto unavailable through-thickness variation of interlaminar (transverse) shear stresses in the vicinity of the bi-layer interface circumferential re-entrant corner line of an... | | 2010-03 |
| 125 |
 |
Liu, Feng | Interplay between quantum size effect and strain effect on growth of nanoscale metal thin films | We develop a theoretical framework to investigate the interplay between the quantum size effect (QSE) and strain effect on the stability of metal nanofilms. The QSE and strain effect are shown to be coupled through the concept of quantum electronic stress. First-principles calculations reveal large ... | | 2012-01-01 |
| 126 |
 |
Liu, Feng | Interplay of stress, structure, and stoichiometry in Ge-covered Si(001) | By calculating the evolution of surface energies and surface stress tensors of Ge-covered Si(001) with increasing Ge coverage, we derive the most probable Ge stoichiometry in the subsurface regions beyond 1 monolayer coverage. We compare the calculated surface reconstruction and surface stress at th... | Ge-covered; Si(001); Stress; Structure; Surface stress tensors | 1996-04 |
| 127 |
 |
Liu, Feng | Intrinsic current-voltage properties of nanowires with four-probe scanning tunneling microscopy: a conductance transition of ZnO nanowire | We report intrinsic current-voltage properties of ZnO nanowire measured by a four-tip scanning tunneling microscopy (F-STM). It is found that after bending the nanowire with the F-STM the conductance is reduced by about five orders of magnitude. The cathodoluminescent spectra indicate that the ZnO n... | ZnO nanowire; Four-probe; Four-tip; F-STM; Conductance transition | 2006 |
| 128 |
 |
Scarpulla, Michael | Investigating sputtered Cu2Si1-xSnxS3 (CSTS) for earth abundant thin film photovoltaics | This 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 |
| 129 |
 |
Scarpulla, Michael | Investigation of combinatorial coevaporated thin film Cu 2ZnSnS4 (II): Beneficial cation arrangement in Cu-rich growth | Cu2ZnSn(S,Se)4 (CZTSSe) is an earth-abundant semiconductor with potential for economical photovoltaic power generation at terawatt scales. In this work, we use Raman scattering to investigate phase coexistence in combinatorial CZTS thin films grown at 325 or 470 C. The surface of the samples grown a... | | 2014-01-01 |
| 130 |
 |
Scarpulla, Michael | Investigation of combinatorial coevaporated thin film Cu 2ZnSnS4. I. Temperature effect, crystalline phases, morphology, and photoluminescence | Cu2ZnSnS4 is a promising low-cost, nontoxic, earth-abundant absorber material for thin-film solar cell applications. In this study, combinatorial coevaporation was used to synthesize individual thin-film samples spanning a wide range of compositions at low (325 C) and high (475 C) temperatures. Film... | | 2014-01-01 |
| 131 |
|
Pugmire, Ronald J. | Investigation of the structural conformation of biphenyl by solid state 13C NMR and quantum chemical NMR shift calculations | The principal values of the 13C chemical-shift tensor (CST) for biphenyl have been determined with the FIREMAT experiment. The internal dihedral angle between the benzene rings in biphenyl is estimated to fall between 10 and 20° on the basis of quantum mechanical calculations of the CST principal v... | Carbon-13; Chemical-shift tensor; biphenyl; FIREMAT | 2001 |
| 132 |
 |
Stringfellow, Gerald B. | Kinetically controlled order/disorder structure in GaInP | A Ga0.52In0.58p order/disorder heterostructure having a band-gap energy difference exceeding 160 meV has been grown by organometallic vapor phase epitaxy. The two layers were grown on a nominally (OOl)-oriented GaAs substrate misoriented by 3° toward the [110] direction in the lattice. The disorder... | Indium phosphides; Gallium Phosphides; Heterojunctions | 1994 |
| 133 |
 |
Liu, Feng | Kinetics of mesa overlayer growth: climbing of adatoms onto the mesa top | We have calculated the energy barriers for an adatom climbing up onto a Pb mesa top either over a facet-facet edge or through a facet-step joint, using a modified embedded atom method. We found that the second process is not only thermodynamically more favorable than the first one but also much fast... | Mesa overlayer growth; Adatoms; Epitaxial growth | 2008 |
| 134 |
 |
Stringfellow, Gerald B. | Kinetics of Te doping in disordering GaInP grown by organometallic vapor phase epitaxy | Te-doped GaInP epitaxial layers were grown by organometallic vapor phase epitaxy in an effort to clarify the Te disordering mechanism. CuPt ordered GaInP is produced under normal growth conditions. The addition of Te has been reported to induce disorder. One suggested mechanism for disordering GaInP... | Crystal growth; Epitaxy; Dynamics | 2001 |
| 135 |
 |
Liu, Feng | Liu et al reply | In our Letter [1], we have demonstrated the plausibility of a structure for ?-cristobalite SiC2 consisting of domains of I Aid symmetry, and provided strong evidence against other proposed models, based on first-principles total energy and lattice dynamics calculations. We are pleased that the Auth... | beta-Cristobalite SiO2; Rigid unit modes; RUM; Transient domain formation | 1993 |
| 136 |
 |
Liu, Feng | Liu et al. reply | In our paper we were alluding to a structural phase transition rather than an order-disorder one. We agree with Blaschko2 that more work needs to be done regarding the statistical mechanics of the hydrogen ordering. This was already acknowledged in our paper when we stated that the model of nonint... | Structural phase transition; Hydrogen ordering; Ising lattice-gas models; Proton glass | 1990 |
| 137 |
 |
Liu, Feng | Local strain-mediated chemical potential control of quantum dot self-organization in heteroepitaxy | From observations of self-assembly of Ge quantum dots directed by substrate morphology, we propose the concept of control of ordering in heteroepitaxy by a local strain-mediated surface chemical potential. Using quite simple lithography, we demonstrate directed quantum dot ordering. The strain part ... | Self-organization; Heteroepitaxy; Chemical potential control; Ge quantum dots | 2004-01 |
| 138 |
 |
Stringfellow, Gerald B. | Long wavelength lattice dynamics for quaternary alloys: GaInPSb and AlGaAsSb | Presents information on a study which investigated the long wavelength lattice dynamics of quaternary alloys. Theory of the random cell isodisplacement model; Secular equation developed; Results and discussion. | Lattice dynamics; Quaternary alloys | 1992 |
| 139 |
 |
Stringfellow, Gerald B.; Sadwick, Laurence P. | Low pressure pyrolysis of alternate phosphorus precursors for chemical beam epitaxial growth of InP and related compounds | The 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; CBE | 1994 |
| 140 |
 |
Scarpulla, Michael | Magnetic cluster phases of Mn-interstitial-free (Ga,Mn)As | We report an investigation of magnetic cluster phases of (Ga,Mn)As of varying dosages formed by Mn ion implantation followed by pulsed-laser melting (II-PLM). A systematic study of zero-field-cooled and field-cooled magnetization along several high-symmetry crystallographic directions reveals the ... | Magnetic cluster phases; Gallium Arsenide; Ferromagnetic semiconductors; Interstitials | 2007 |
| 141 |
 |
Liu, Feng | Magnetism and local order II: self-consistent cluster calculations | The effect of the local environment on the magnetic moment and its convergence to bulk value has been studied self-consistently by using a molecular-cluster model within the framework of spin-density-functional theory. We show that the magnetic moment of the central atom in clusters of 43 Ni atoms a... | Local order; Magnetic moment; Molecular-cluster model; Spin-density-functional theory | 1989-07 |
| 142 |
 |
Liu, Feng | Magnetism and local order: ab initio tight-binding theory | The effects of the local environment on the electronic structure and magnetic moments of Fe, Co, and Ni have been studied by confining these atoms to assume various structural forms such as chains, surfaces, layers, and crystals. The coordination number of the atoms can thus be changed over a wide r... | Local order; Ab-initio tight-binding theory; Magnetic moment; Electronic structure; Fe; Co; Ni | 1989-04 |
| 143 |
 |
Liu, Feng | Magnetism in nanopatterned graphite film | Using first-principles calculations, we show that nanopatterned graphite films (NPGFs) can exhibit magnetism in analogy to graphene-based nanostructures (GBNs). In particular, graphite films with patterned nanoscale triangular holes and channels with zigzag edges all have ferromagnetic ground state... | Nanopatterned graphite; Graphite films; NPGF | 2008 |
| 144 |
 |
Liu, Feng | Magnetism in small vanadium clusters | Using the self-consistent-field molecular-orbital theory and the density-functional approximation, we show that vanadium could become magnetic if its size and dimension were constrained. This is illustrated for vanadium forming clusters with body-centered-cubic (bcc) geometry as well as for linear c... | Vanadium clusters; Molecular-orbital theory; Density-functional approximation; Stoner criterion | 1991-04 |
| 145 |
 |
Liu, Feng | Magnetism of Al-Mn quasicrystals | The effect of symmetry and concentration of Mn on the magnetism of Al-Mn quasicrystals has been investigated through self-consistent density-functional calculations using molecular clusters and supercell band-structure schemes. A single Mn atom surrounded by 54 Al atoms in an icosahedral or a cuboct... | Al-Mn quasicrystals; Self-consistent; Density-functional calculations | 1993-07 |
| 146 |
 |
Liu, Feng | Magnetization on rough ferromagnetic surfaces | Using Ising-model Monte Carlo simulations, we show a strong dependence of surface magnetization on surface roughness. On ferromagnetic surfaces with spin-exchange coupling larger than that of the bulk, the surface magnetic ordering temperature decreases toward the bulk Curie temperature with incre... | Ferromagnetic surfaces; Surface magnetization | 2000-11 |
| 147 |
 |
Liu, Feng | Magnetization on vicinal ferromagnetic surfaces | Using Ising model Monte Carlo simulations, we show a strong dependence of surface magnetization on surface miscut angle. For ferromagnetic surfaces, when surface spin exchange coupling is larger than that of the bulk, the surface magnetic ordering temperature decreases, toward the bulk Curie tempera... | Vicinal ferromagnetic surfaces; Surface magnetization; Surface miscut angle | 1997 |
| 148 |
 |
Scarpulla, Michael | Magnetocrystalline anisotropy and magnetization reversal in Ga1-xMnxP synthesized by ion implantation and pulsed-laser melting | We report the observation of ferromagnetic resonance (FMR) and the determination of the magnetocrystalline anisotropy in (100)-oriented single-crystalline thin film samples of Ga1−xMnxP with x=0.042. The contributions to the magnetic anisotropy were determined by measuring the angular and the te... | Magnetocrystalline anisotropy; GaMnAs; Gallium arsenide | 2007-06 |
| 149 |
 |
Liu, Feng | Making a field effect transistor on a single graphene nanoribbon by selective doping | Using first-principles electronic structure calculations, we show a metal-semiconductor transition of a metallic graphene nanoribbon with zigzag edges induced by substitutional doping of nitrogen or boron atoms at the edges. A field effect transistor consisting of a metal-semiconductor-metal junctio... | Graphene nanoribbon; Selective doping | 2007 |
| 150 |
 |
Tiwari, Ashutosh | Manifestation of two-channel nonlocal spin transport in the shapes of Hanle curves | The dynamics of charge-density fluctuations in a system of two tunnel-coupled wires contains two diffusion modes with dispersion iω = Dq2 and iω = Dq2 + 2τt, where D is the diffusion coefficient and τt is the tunneling time between the wires. The dispersion of corresponding spin-density modes de... | | 2014-01-01 |
| 151 |
 |
Liu, Feng | Mechanical stability of ultrathin Ge/Si film on SiO2: the effect of Si/SiO2 interface | We perform two-dimensional linear elastic finite element analysis to investigate the mechanical stability of ultrathin Ge/Si film grown on or bonded to SiO2, using imperfect interface elements between Si and SiO2 to model Si/SiO2 interfacial slippage. We demonstrate that the overall composite film i... | Ultrathin films; Si/SiO2 interface; Mechanical stability | 2005 |
| 152 |
 |
Stringfellow, Gerald B. | Mechanism for liquid phase epitaxial growth of nonequilibrium compositions producing a coherent interface | A model is presented for growth by so-called composition pulling, wherein an epitaxial deposit grows coherently but with a composition different from that which would be in bulk equilibrium with the liquid phase from which growth occurs. The breakdown of coherent growth occurs when a dislocation nuc... | Lattice-matching overgrowths; Composition pulling; Dislocation interface | 1977 |
| 153 |
 |
Liu, Feng | Mechanism for nanotube formation from self-bending nanofilms driven by atomic-scale surface-stress imbalance | We demonstrate, by theoretical analysis and molecular dynamics simulation, a mechanism for fabricating nanotubes by self-bending of nanofilms under intrinsic surface-stress imbalance due to surface reconstruction. A freestanding Si nanofilm may spontaneously bend itself into a nanotube without exter... | Nanotube formation; Self-bending nanofilms; Surface-stress imbalance | 2007-04 |
| 154 |
 |
Tiwari, Ashutosh | Metal-insulator transition in La0.7Sr0.3Mn1-xFexO3 | We report the effect of Fe doping at the Mn site in La0.7Sr0.3MnO3 oxides. We find that the doping of Fe does not cause any structural change, but the electrical transport in the system is strongly affected. The parent compound La0.7Sr0.3MnO3 shows a resistivity peak at T=Tp (365 K) and behaves as ... | Tunneling conductance; Perovskite manganates; Iron doping; Fe doping | 1999 |
| 155 |
 |
Liu, Feng | Metal-to-semiconductor transition in squashed armchair carbon nanotubes | We investigate electronic transport properties of the squashed armchair carbon nanotubes, using tight-binding molecular dynamics and the Green's function method. We demonstrate a metal-to-semiconductor transition while squashing the nanotubes and a general mechanism for such a transition. It is the ... | Squashed armchair; Carbon nanotubes; Metal-to-semiconductor transition; Electronic transport; Tight-binding molecular dynamics; Squashed nanotubes | 2003-04 |
| 156 |
 |
Tiwari, Ashutosh | Metallic conductivity and metal-semiconductor transition in Ga-doped ZnO | This letter reports the metallic conductivity in Ga:ZnO system at room temperature and a metal-semiconductor transition (MST) behavior at low temperatures. Zn0.95Ga0.05O films, deposited by pulsed laser deposition in the pressure range of ~10−2 Torr of oxygen, were found to be crystalline and exhi... | Transparent conducting oxides; ZnO; Gallium; Metallic conductivity | 2006 |
| 157 |
 |
Tiwari, Ashutosh | Methods of forming three-dimensional nanodot arrays in a matrix | Nanostructures and methods of making nanostructures having self-assembled nanodot arrays wherein nanodots are self-assembled in a matrix material due to the free energies of the nanodot material and/or differences in the Gibb's free energy of the nanodot materials and matrix materials. | Nanodots | 2006 |
| 158 |
 |
Tiwari, Ashutosh | Mid- to long-wavelength infrared surface plasmon properties in doped zinc oxides | This work investigates properties of surface plasmons on doped metal oxides in the 2-20 μm wavelength regime. By varying the stoichiometry in pulse laser deposited Ga and Al doped ZnO, the plasmonic properties can be controlled via a fluctuating free carrier concentration. This deterministic approa... | | 2012-01-01 |
| 159 |
 |
Stringfellow, Gerald B. | Miscibility gaps and spinodal decomposition in III/V quaternary alloys of the type AxByC1−x−yD | Thermodynamic concepts have been developed for the calculation of solid-phase miscibility gaps and spinodal decomposition in quaternary alloys of the type AxByC1−x−yD. These concepts have been applied to the analysis of III/V quaternary alloys using the delta-lattice-parameter (DLP) solution mod... | Thermodynamics; Quartenary alloys; Coherent decomposition | 1983-01 |
| 160 |
 |
Scarpulla, Michael | Mn L3,2 x-ray absorption and magnetic circular dichroism in ferromagnetic Ga1-xMnxP | We have measured the x-ray absorption and x-ray magnetic circular dichroism (XMCD) at the Mn L3,2 edges in ferromagnetic Ga1−xMnxP films for 0.018≤x≤0.042. Large XMCD asymmetries at the L3 edge indicate significant spin polarization of the density of states at the Fermi energy. The temperatur... | X-ray absorption; Gallium Arsenide; Ferromagnetic semiconductors | 2006 |
| 161 |
 |
Scarpulla, Michael | Mn L3,2 x-ray absorption spectroscopy and magnetic circular dichroism in ferromagnetic Ga1-xMnxP | We have measured the X-ray absorption (XAS) and X-ray magnetic circular dichroism (XMCD) at the Mn i32 edges in ferromagnetic Ga1-xMrixP films for 0.018<x<0.042. Large XMCD asymmetries at the L3 edge indicate significant spin-polarization of the density of states at the Fermi energy. The spectral s... | X-ray absorption; Ferromagnetic semiconductors; X-ray magnetic circular dichroism (XMCD); Gallium Manganese Phosphide; Gallium arsenide | 2007 |
| 162 |
 |
Tiwari, Ashutosh | Modification of high potential, high capacity Li2FeP 2O7 cathode material for lithium ion batteries | Li2FeP2O7 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 |
| 163 |
 |
Liu, Feng | Modification of Si(001) substrate bonding by adsorbed Ge or Si dimer islands | High-resolution scanning tunneling microscopy studies of the Si(100)-(2 X 1) surface show a heretofore unrecognized distortion of the substrate structure when islands form during the initial stage of growth of either Si or Ge. The distortion, reflecting the influence of strain, extends at least thre... | Si(001); Adsorbed Ge; Adsorbed Si; Dimer islands; Substrate bonding; Distortion | 1998-09 |
| 164 |
 |
Liu, Feng | Modified Timoshenko formula for bending of ultrathin strained bilayer films | Mechanical bending of nanoscale thin films can be quite different from that of macroscopic thick films. However, current understanding of mechanical bending of nanoscale thin strained bilayer films is often limited within the Timoshenko model [Timoshenko, J. Opt. Soc. Am. 11, 233 (1925)], which was ... | Timoshenko formula; Bending theory; Ultrathin films; Strained nanoscale thin films; Nanofilms | 2008 |
| 165 |
|
Smith, Grant D. | Molecular dynamics of a 1,4-polybutadiene melt. Comparison of experiment and simulation | We have made detailed comparison of the local and chain dynamics of a melt of 1,4-polybutadiene (PBD) as determined from experiment and molecular dynamics simulation at 353 K. The PBD was found to have a random microstructure consisting of 40% cis, 50% trans, and 10% 1,2-vinyl units with a number-av... | Polybutadiene melt; Molecular dynamics | 1999 |
| 166 |
 |
Smith, Grant D. | Molecular dynamics simulation studies of the influence of imidazolium structure on the properties of imidazolium/azide ionic liquids | Atomistic 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 |
| 167 |
 |
Bedrov, Dmitro; Smith, Grant D. | Molecular dynamics simulation study of elastic properties of HMX | Atomistic simulations were used to calculate the isothermal elastic properties for b-, a-, and d-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). The room-temperature isotherm for each polymorph was computed in the pressure interval 0≤p≤10.6 GPa and was used to extract the initial isot... | HMX; Elastic tensors; Isotropic moduli; Polymorphs; Isothermal compression; Lattice parameters | 2003 |
| 168 |
 |
Bedrov, Dmitro | Molecular dynamics simulation study of the pressure-volume-temperature behavior of polymers under high pressure | Isothermal compression of poly (dimethylsiloxane), 1,4-poly(butadiene), and a model Estane® (in both pure form and a nitroplasticized composition similar to PBX-9501 binder) at pressures up to 100 kbars has been studied using atomistic molecular dynamics (MD) simulations. Comparison of predicted co... | | 2009 |
| 169 |
 |
Bedrov, Dmitro; Smith, Grant D. | Molecular dynamics simulations of HMX crystal polymorphs using a flexible molecule force field | Molecular dynamics simulations using a recently developed quantum chemistry-based atomistic force field [J. Phys. Chem. B 103 (1999) 3570] were performed in order to obtain unit cell parameters, coefficients of thermal expansion, and heats of sublimation for the three pure crystal polymorphs of octa... | HMX; Crystal polymorphs; Force field; Coefficients of thermal expansion; Heat of sublimation; Cell parameters | 2002 |
| 170 |
 |
Smith, Grant D.; Borodin, Oleg | Molecular-dynamics simulation study of dielectric relaxation in a 1,4-polybutadiene melt | We have carried out atomistic molecular dynamics simulations of a melt of 1,4-poly(butadiene) from temperatures well above the experimentally observed merging of the primary a process and secondary b process down to temperatures approaching the experimentally observed bifurcation temperature. The re... | Polymer melts; 1,4-polybutadiene; Chain dynamics; Conformational dynamics | 2002 |
| 171 |
 |
Ostafin, Agnes | Monitoring the synthesis and composition analysis of microsilica encapsulated acetylacetonatocarbonyl triphenylphosphinerhodium catalyst by inductively coupled plasma (ICP) techniques | Abstract-A novel technique to monitor the synthesis process of encapsulated acetylacetonatocarbonyl triphenylphosphinerhodium within a microsilica nanoshell has been studied using inductively coupled plasma (ICP) techniques. Nanospheres sized around 50-100 nm were obtained and ICP was used to quanti... | | 2006 |
| 172 |
 |
Scarpulla, Michael | Mutual passivation of group IV donors and nitrogen in diluted GaNxAs1 x alloys | We demonstrate the mutual passivation phenomenon of Ge donors and isovalent N in highly mismatched alloy GaNxAs1-x doped with Ge. Layers of this alloy were formed by the sequential implantation of Ge and N ions followed by pulsed laser melting and rapid thermal annealing. The mutual passivation effe... | Highly mismatched alloys; Passivation; Gallium arsenide | 2003 |
| 173 |
 |
Ostafin, Agnes | Nanomedicine making headway across the blood brain barrier | Nanotechnological 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 |
| 174 |
 |
Liu, Feng | Nanostressors and the nanomechanical response of a thin silicon film on an insulator | Pseudomorphic three-dimensional Ge nanocrystals (quantum dots) grown on thin silicon-on-insulator substrates can induce significant bending of the silicon template layer that is local on the nanometer scale. We use molecular dynamics simulations and analytical models to confirm the local bending of... | Nanostressors; Nanomechanical response; Thin silicon film | 2002-09 |
| 175 |
 |
Tiwari, Ashutosh | Nanostructured DLC-Ag composites for biomedical applications | We have synthesized novel diamondlike carbon coatings with silver nanoparticles embedded into the DLC film. The size of silver nanoparticles that are confined into layered structures has been varied from 5 nm to 50 nm using an ingenious pulsed laser deposition technique. The size of nanoparticles wa... | Diamondlike carbon coatings; Nanocrystals | 2003 |
| 176 |
 |
Liu, Feng | Nature of reactive O2 and slow CO2 evolution kinetics in CO oxidation by TiO2 supported Au cluster | Recent experiments on CO oxidation reaction using seven-atom Au clusters deposited on TiO2 surface correlate CO2 formation with oxygen associated with Au clusters. We perform first principles calculations using a seven-atom Au cluster supported on a reduced TiO2 surface to explore potential candidat... | Au clusters; TiO2; Kinetic evolution | 2006 |
| 177 |
 |
Scarpulla, Michael | Near-infrared absorption and semimetal-semiconductor transition in 2 nm ErAs nanoparticles embedded in GaAs and AlAs | We report strong near-infrared absorption peaks in epitaxial films of GaAs and AlAs containing approximately 0.5-5% of the semimetal ErAs. The energy of the resonant absorption peak can be changed from 0.62 to 1.0 eV (2.2-1.4 μm) by variation of the ErAs volume fraction and the substrate temperatu... | Near-infrared absorption; Semimetal-semiconductor transition; GaAs; AlAs; ErAs; Gallium arsenide; Aluminum arsenide | 2008 |
| 178 |
 |
Scarpulla, Michael | New methodologies for measuring film thickness, coverage, and topography | We describe how the techniques of X-ray reflectivity (XRR), electron spectroscopy for chemical analysis (ESCA), and atomic force microscopy (AFM) can be used to obtain the structural parameters-thickness, coverage, and topography-of thin films used on magnetic recording disks. We focus on ultra-thi... | Atomic force microscopy; Electron spectroscopy for chemical analysis; X-ray reflectivity | 2000-01 |
| 179 |
 |
Stringfellow, Gerald B. | Nitrogen surfactant effects in GaInP | The addition of surfactant nitrogen during the growth of GaInP on 001 GaAs substrates produces significant and interesting changes in the optical and morphological properties of GaInP. In particular, multiple peaks are seen in the low temperature photoluminescence (PL) spectra of GaInP/GaInP:N he... | Surfactant nitrogen; Microscopy; Crystals | 2004 |
| 180 |
|
Smith, Grant D.; Bedrov, Dmitro | NMR experiments and molecular dynamics simulations of the segmental dynamics of polystyrene | We have performed NMR spin?lattice relaxation experiments and molecular dynamics (MD) computer simulations on atactic polystyrene (a-PS). The segmental correlation times of three different molecular weight a-PS (Mn = 1600, 2100, 10 900 g/mol) were extracted from NMR by measuring the 2H spin?lattice ... | | 2004 |
| 181 |
 |
Scarpulla, Michael | Nonmagnetic compensation in ferromagnetic Ga1-xMnxAs and Ga1-xMnxP synthesized by ion implantation and pulsed-laser melting | The electronic and magnetic effects of intentional compensation with nonmagnetic donors are investigated in the ferromagnetic semiconductors Ga1−xMnxAs and Ga1−xMnxP synthesized using ion implantation and pulsed-laser melting. It is demonstrated that compensation with nonmagnetic donors and MnI ... | Ferromagnetic semiconductors | 2008 |
| 182 |
 |
Tiwari, Ashutosh | Observation of the inverse spin hall effect in ZnO thin films: an all-electrical approach to spin injection and detection | The inverse spin Hall effect (ISHE) is a newly discovered, quantum mechanical phenomenon where an applied spin current results in the generation of an electrical voltage in the transverse direction. It is anticipated that the ISHE can provide a more simple way of measuring spin currents in spintroni... | | 2014-01-01 |
| 183 |
 |
Shetty, Dinesh K. | On the effect of birefringence on light transmission in Polycrystalline Magnesium Fluoride | Light transmission in polycrystalline magnesium fluoride was studied as a function of the mean grain size at different wavelengths. The mean grain size was varied by annealing hot-pressed billets in argon atmosphere at temperatures ranging from 600 to 800°C for 1 hour. The grain-size and grain-orie... | | 2014-01-01 |
| 184 |
 |
Smith, Grant D. | On the non-Gaussianity of chain motion in unentangled polymer melts | We have investigated chain dynamics of an unentangled polybutadiene melt via molecular dynamics simulations and neutron spin echo experiments. Good short-time statistics allows for the first experimental confirmation of subdiffusive motion of polymer chains for times less than the Rouse time (T R) c... | Polymer melts; Chain dynamics; 1,4-polybutadiene melts; Neutron spin echo | 2001 |
| 185 |
 |
Chaudhuri, Reaz A. | On three-dimensional singular stress/residual stress fields at the front of a crack/anticrack in an orthotropic/orthorhombic plate under anti-plane shear loading | A novel eigenfunction expansion technique, based in part on separation of the thickness-variable, is developed to derive three-dimensional asymptotic stress field in the vicinity of the front of a semi-infinite through-thickness crack/anticrack weakening/reinforcing an infinite orthotropic/orthorhom... | | 2010-07 |
| 186 |
 |
Liu, Feng | Orbit- and atom-resolved spin textures of intrinsic, extrinsic, and hybridized Dirac cone states | Combining first-principles calculations and spin- and angle-resolved photoemission spectroscopy measurements, we identify the helical spin textures for three different Dirac cone states in the interfaced systems of a two-dimensional (2D) topological insulator (TI) of a Bi(111) bilayer and a three-di... | | 2014-01-01 |
| 187 |
 |
Stringfellow, Gerald B. | Organometallic vapor phase epitaxial growth of AlGaInP | Alx Ga,, In, _ x _ y P with x + y = 0.51, lattice matched to the GaAs substrate, has been grown by organometaUic vapor phase epitaxy. The simple, horizontal, IR heated system operates at atmospheric pressure using the reactants TMA1, TMGa, TMln, PH3, and K2. Alloys giving room temperature, band edge... | Liquid phase epitaxial growth; LPE; Alloys; Surface morphology | 1985 |
| 188 |
 |
Stringfellow, Gerald B.; Cohen, Richard M. | Organometallic vapor phase epitaxial growth of high purity GaInAs using trimethylindium | Gax In1−xAs lattice matched to the InP substrate (x=0.47) has been grown by organometallic vapor phase epitaxy using trimethylindium (TMIn) and trimethylgallium (TMGa) as the group III sources and AsH3 as the As source. In a simple, horizontal, atmospheric pressure reactor, the GaInAs growth proce... | Electron mobilities; Photouminescience; Fabricate modulation | 1984-03-01 |
| 189 |
 |
Liu, Feng | Origin of intergranular embrittlement of Al alloys induced by Na and Ca segregation: grain boundary weakening | Using a first-principles computational tensile test, we show that the ideal tensile strength of an Al grain boundary (GB) is reduced with both Na and Ca GB segregation. We demonstrate that the fracture occurs in the GB interface, dominated by the break of the interfacial bonds. Experimentally, we f... | Intergranular embrittlement; Grain boundary; Intergranular fracture | 2006-06 |
| 190 |
 |
Tiwari, Ashutosh | Oxides for spintronics: a review of engineered materials for spin injection | In this article we have reviewed the role of oxides in spintronics research, and specifically how these materials stand to further improve the efficiencies and capabilities of spin injection for active spintronic device development. The use of oxides in spintronics is advantageous in that they are s... | | 2014-01-01 |
| 191 |
 |
Liu, Feng | Pattern formation on silicon-on-insulator | The strain driven self-assembly of faceted Ge nanocrystals during epitaxy on Si(001) to form quantum dots (QDs) is by now well known. We have also recently provided an understanding of the thermodynamic driving force for directed assembly of QDs on bulk Si (extendable to other QD systems) based on ... | Pattern formation; Silicon-on-insulator; Strain driven; Faceted Ge nanocrystals; Si(001); Directed assembly | 2005 |
| 192 |
 |
Liu, Feng | Pattern formation via a two-step faceting transition on vicinal Si(111) surfaces | We demonstrate a self-organized pattern formation on vicinal Si(l 11) surfaces that are miscut toward the [211] direction. All the patterns, consisting of a periodic array of alternating (7x7) reconstructed terraces and step-bunched facets, have the same periodicity and facet structure, independent ... | Pattern formation; Faceting transition; Vicinal Si(111); Miscut | 2001 |
| 193 |
 |
Stringfellow, Gerald B. | Photoluminescence of Shallow Acceptors in Epitaxial AlGaAs | The low-temperature (2 K) photoluminescence (PL) of AlxGa1-xAs (0<x<0.25 was studied in an effort to characterize shallow acceptors in material grown by organometallic vapor phase epitaxy and liquid phase epitaxy techniques. The dominant shallow acceptor in nominally undoped AlxGa1-xAs specimens gro... | Photoluminescence; Acceptors; Doping | 1980 |
| 194 |
 |
Liu, Feng | Physical origin of hydrogen-adsorption-induced metallization of the SiC surface: n-type doping via formation of hydrogen bridge bond | We perform first-principles calculations to explore the physical origin of hydrogen-induced semiconductor surface metallization observed in β-SiC(001)-3 x 2 surface. We show that the surface metallization arises from a novel mechanism of n-type doping of surface band via formation of hydrogen bri... | Metallization; Hydrogen adsorption; SiC; n-type doping; Hydrogen bridge bond | 2005-10 |
| 195 |
|
Borodin, Oleg; Smith, Grant D.; Bedrov, Dmitro | Polarizable and nonpolarizable force fields for alkyl nitrates | Quantum-chemistry-based many-body polarizable and two-body nonpolarizable atomic force fields were developed for alkyl nitrate liquids and pentaerythritol tetranitrate (PETN) crystal. Bonding, bending, and torsional parameters, partial charges, and atomic polarizabilities for the polarizable force f... | Alkyl nitrate; Pentaerythritol tetranitrate; PETN; Polarizable atomic force fields; Nonpolarizable atomic force fields | 2007 |
| 196 |
 |
Liu, Feng | Prediction of a Dirac state in monolayer TiB2 | We predict the existence of a Dirac state in a monolayer TiB2 sheet (m-TiB2), a two-dimensionalmetal diboride, based on first-principles calculations. The band structure of m-TiB2 is found to be characterized with anisotropic Dirac cones with the largest Fermi velocity of 0.57 × 106 m/s, which is a... | | 2014-01-01 |
| 197 |
|
Smith, Grant D. | Prediction of the linear viscoelastic shear modulus of an entangled polybutadiene melt from simulation and theory | While accurate quantum chemistry based potentials,1 improved simulation algorithms, and faster computers have made accurate calculation of chain dynamics in unentangled polymer melts from molecular dynamics simulations possible,2-5 direct calculation of the viscoelastic properties of entangled polym... | Polybutadiene melt; Viscoelastic shear; Chain dynamics; Entangled polymers | 2000 |
| 198 |
 |
Liu, Feng | Pressure-induced hard-to-soft transition of a single carbon nanotube | We demonstrate a hydrostatic pressure-induced hard-to-soft transition of an isolated single wall carbon nanotube, using classical and ab initio constant-pressure molecular-dynamics simulations and continuum elastic theory analysis. At low pressure, the carbon tube is hard. Above a critical pressur... | Carbon nanotubes; Hard-to-soft transition | 2004-10 |
| 199 |
 |
Liu, Feng | Pressure-induced transition in magnetoresistance of single-walled carbon nanotubes | We applied hydrostatic pressure (up to 10 GPa) to single-walled carbon nanotube bundles at low temperature (down to 2 K) to measure their magnetoresistance (MR) in a field up to 12 T. We found a pressure-induced transition in MR from positive to negative in the high-field regime. The onset of the tr... | Single-walled carbon nanotubes; Pressure-induced | 2006-07 |
| 200 |
 |
Scarpulla, Michael | Probing semiconductor band structures and heterojunction interface properties with ballistic carrier emission: GaAs/AlxGa1-xAs as a model system | Utilizing three-terminal tunnel emission of ballistic electrons and holes in a planar tunnel transistor with a Mott-barrier collector, we have developed a method to self-consistently determine the energy gap of a semiconductor and band discontinuities at a semiconductor heterojunction without using... | | 2010-06 |
