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76 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
77 Tiwari, AshutoshEpitaxial growth and properties of Zn1-xVxO diluted magnetic semiconductor thin filmsHere 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; Vanadium2005
78 Tiwari, AshutoshEpitaxial growth of TaN films on Si(100) and Si(111) using a TiN buffer layerWe 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 substrate2002
79 Tiwari, AshutoshEpitaxial 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 strain2002
80 Liu, FengEpitaxial growth of large-gap quantum spin Hall insulator on semiconductor surface : The substrate orbital filtering effectFormation 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
81 Tiwari, AshutoshEpitaxial growth of magnetic nickel nanodots by pulsed laser depositionEpitaxial 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; Nickel2003
82 Bedrov, Dmitro; Smith, Grant D.Equilibrium sampling of self-associating polymer solutions: a parallel selective tempering approachWe 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 tempering2005
83 Liu, FengEquilibrium shape of two-dimensional islands under stressWe 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; Homoepitaxy2000-08
84 Scarpulla, MichaelExact field solution to guided wave progagation in lossy thin filmsWave 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, FengExceptional optoelectronic properties of hydrogenated bilayer siliceneSilicon 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, FengExotic electronic states in the world of flat bands: from theory to materialIt 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, AshutoshExperiments along coexistence near tricriticality in 3He-4He mixturesThe 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 mixtures2000
88 Bedrov, Dmitro; Smith, Grant D.Exploration of conformational phase space in polymer melts: a comparison of parallel tempering and conventional molecular dynamics simulationsParallel 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 tempering2001
89 Liu, FengFabricating artificial nanowells with tunable size and shape by using scanning tunneling microscopyThe 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 nanowells2006
90 Tiwari, AshutoshFabrication and characterization of Li7La3Zr 2O12 thin films for lithium ion batteryThin 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, MichaelFabrication of GaNxAs1-x quantum structures by focused ion beam patterningA 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 annealing2005
92 Scarpulla, MichaelFerromagnetic Ga1-xMnxAs produced by ion implantation and pulsed-laser meltingWe 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 magnetization2003
93 Scarpulla, MichaelFerromagnetic resonance investigation of magnetic anisotropy in Ga1-xMnxAs synthesized by ion implantation and pulsed laser meltingA 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 arsenide2009-12
94 Tiwari, AshutoshFerromagnetism in Co doped CeO2: observation of giant magnetic moment with a high Curie temperatureWe 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; Cobalt2006
95 Tiwari, AshutoshFerromagnetism in Cu-doped ZnO films: role of charge carriersWe 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 carriers2008
96 Scarpulla, MichaelFerromagnetism in Ga1-xMnxP: evidence for inter-Mn exchange mediated by localized holes within a detached impurity bandWe 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 band2005-11
97 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
98 Liu, FengFirst-principles studies on structural properties of β-cristobaliteThe 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 algorithm1993-05
99 Liu, FengFirst-principles study of crystalline silicaWe 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 pseudopotential1994-05
100 Liu, FengFirst-principles study of electronic properties of biaxially strained silicon: effects on charge carrier mobilityUsing 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 theory2008-12
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