UScholar Works
 
Filters: Department: "Materials Science & Engineering" Journal Title: "Journal of Applied Physics" Collection: ir_uspace
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CreatorTitleDescriptionSubjectDate
1 Tiwari, AshutoshBand-gap engineering of Zn1-xGaxO nanopowders: synthesis, structural and optical characterizationsWe report the preparation and detailed structural and optical characterizations of single phase gallium doped ZnO nanopowders. A low temperature solution-based technique was developed to synthesize high-purity Zn1−xGaxO (x:0-0.05) nanopowders. Structural and optical characterization experiments we...Zinc gallium oxide; ZnGaO; Nanopowders; Band-gap engineering2008
2 Liu, FengEffect of size and dimensionality on the magnetic moment of transition metalsThe 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; Ni1990
3 Stringfellow, Gerald B.; Rieth, Loren W.Effects of Br and Cl on organometallic vapor phase epitaxial growth and ordering in GaInPCuPt 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 processes2004
4 Tiwari, AshutoshElectrical properties of transparent and conducting Ga doped ZnOIn 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 conductivity2006
5 Scarpulla, MichaelElectrical transport and ferromagnetism in Ga1−xMnxAs synthesized by ion implantation and pulsed-laser meltingWe 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 arsenide2008
6 Tiwari, AshutoshElectrical transport in ZnO1-δ films: transition from band-gap insulator to Anderson localized insulatorWe 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 insulators2004
7 Liu, FengEnhanced growth instability of a strained film on wavy substrateWe 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-assembly2008
8 Tiwari, AshutoshEpitaxial growth and properties of MoOx(2We 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; MoO2005
9 Liu, FengFirst-principles calculation of interaction between interstitial O and As dopant in heavily As-doped SiWe 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; Oi2007
10 Tiwari, AshutoshFormation of self-assembled epitaxial nickel nanostructuresHighly 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; Nickel2003
11 Scarpulla, MichaelHeat flow model for pulsed laser melting and rapid solidification of ion implanted GaAsIn 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
12 Stringfellow, Gerald B.Influence of Sb, Bi, Tl, and B on the incorporation of N in GaAsGaAs: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; Nitrogen2002
13 Stringfellow, Gerald B.Kinetics of Te doping in disordering GaInP grown by organometallic vapor phase epitaxyTe-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; Dynamics2001
14 Liu, FengMechanical stability of ultrathin Ge/Si film on SiO2: the effect of Si/SiO2 interfaceWe 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 stability2005
15 Tiwari, AshutoshMetal-insulator transition in La0.7Sr0.3Mn1-xFexO3We 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 doping1999
16 Stringfellow, Gerald B.Nitrogen surfactant effects in GaInPThe 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; Crystals2004
17 Scarpulla, MichaelNonmagnetic compensation in ferromagnetic Ga1-xMnxAs and Ga1-xMnxP synthesized by ion implantation and pulsed-laser meltingThe 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 semiconductors2008
18 Stringfellow, Gerald B.Spectroscopic study of surfactant enhanced organometallic vapor phase epitaxy growth of GaInPSamplen s of GaxIn1-xP grown by organometallic vapor phase epitaxy on (001) GaAs substrates by addition of TESb demonstrating a lateral superlattice compositional modulation (CM) have been studied by low temperature polarized photoluminescence (PL), power dependent PL, and photoluminescence excitati...Organometallic vapor; Photoluminescence excitation; Spectroscopy2001
19 Liu, FengStep-induced magnetic-hysteresis anisotropy in ferromagnetic thin filmsWe investigate the quasistatic magnetic hysteresis of ferromagnetic thin films grown on a vicinal substrate, using Monte Carlo simulations within a two-dimensional XY model. Intrinsic in-plane anisotropy is assigned to surface sites according to their local symmetry. The simulated hysteresis loops s...Magnetic hysteresis; Ferromagnetic thin films; Step-induced2002
20 Tiwari, AshutoshStructural, electrical, and optical characterizations of epitaxial Zn(1-x)Ga(x)O films grown on sapphire (0001) substrateIn this paper we report the structural, electrical, and optical properties of epitaxial Zn1−xGaxO films (x=0-0.05) grown on single crystal sapphire (0001) substrate by pulsed laser deposition technique. Structural and elemental analysis was performed using high-resolution x-ray diffraction (θ-2...Transparent conductive oxides; Gallium2007
21 Scarpulla, MichaelSuppression of hole-mediated ferromagnetism in Ga1-xMnxP by hydrogenWe report the passivation of the Mn acceptors in Ga1−xMnxP upon exposure to a hydrogen plasma. The as-grown films are nonmetallic and ferromagnetic with a Curie temperature of TC=55 K. After hydrogenation the sample resistivity increases by approximately three orders of magnitude at room tempera...Ferromagnetic semiconductors; Hydrogenation2008
22 Scarpulla, MichaelSynthesis and optical properties of II-O-VI highly mismatched alloysWe have synthesized ternary and quaternary diluted II-VI oxides using the combination of O ion implantation and pulsed laser melting. CdOxTe12x thin films with x up to 0.015, and the energy gap reduced by 150 meV were formed by O1-implantation in CdTe followed by pulsed laser melting. Quaternary Cd0...Highly mismatched alloys; Cadmium telluride; Zinc telluride; Thermal annealing; Anticrossing; Photomodulation spectroscopy2004
23 Scarpulla, MichaelSynthesis of GaNxAs1-x thin films by pulsed laser melting and rapid thermal annealing of N+-implanted GaAsWe present a systematic investigation on the formation of the highly mismatched alloy GaNxAs1-x using N1-implantation followed by a combination of pulsed laser melting and rapid thermal annealing. Thin films of GaNxAs1-x with x as high as 0.016 and an activation efficiency of the implanted N up to 5...Highly mismatched alloys; Gallium arsenide2003
24 Stringfellow, Gerald B.Use of Nitrogen to disorder GaInPSignificant changes in microstructure, surface structure, and alloy composition have been observed in GaInP with the addition of nitrogen. These effects occur due to surface changes induced by small concentrations of nitrogen. Transmission electron microscopy and photoluminescence experiments indica...Nitrogen; Alloys; Transmission2004
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