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Creator | Title | Description | Subject | Date |
26 |
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Liu, Feng | Strain-engineered surface transport in Si(001): complete isolation of the surface state via tensile strain | By combining density functional theory, nonequilibrium Green's function formulism and effective- Hamiltonian approaches, we demonstrate strain-engineered surface transport in Si(001), with the complete isolation of the Si surface states from the bulk bands. Our results show that sufficient tensile s... | | 2013-01-01 |
27 |
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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 |
28 |
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Tiwari, Ashutosh | Room-temperature solid-state radiation detectors based on spintronics | In this paper we are presenting a unique approach to solve the thermal background problem encountered in semiconductor nuclear detectors. Our approach addresses above challenge by making a shift from 'electronic detection mechanism' to 'spintronic detection mechanism'. The proposed methodology is ba... | | 2012-01-01 |
29 |
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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 |
30 |
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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 |
31 |
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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 |
32 |
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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 |
33 |
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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 |
34 |
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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 |
35 |
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Scarpulla, Michael | Pulsed and continuous wave solid phase laser annealing of electrodeposited CuInSe2 thin films | Cu(In,Ga)Se2 (CIGS) thin film photovoltaic absorber layers are primarily synthesized by vacuum based techniques at industrial scale. In this work, we investigate non-vacuum film synthesis by electrochemical deposition coupled with pulsed laser annealing (PLA) and or continuous wave laser annealing (... | | 2012-01-01 |
36 |
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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 |
37 |
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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 |
38 |
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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 |
39 |
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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 |
40 |
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Scarpulla, Michael | Pulsed laser processing of electrodeposited CuInSe2 photovoltaic absorber thin films | In this report we investigate the effects of pulsed laser annealing (PLA) on both as-electrodeposited (ED) and electrodeposited-furnace annealed (EDA) CuInSe2 (CIS) samples by varying the laser fluence (J/cm2) and number of pulses. Results for as-ED samples indicate that liquid CIS-phase formation d... | | 2011-01-01 |
41 |
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Liu, Feng | Topological and electronic transitions in a Sb(111) nanofilm: the interplay between quantum confinement and surface effect | When the dimension of a solid structure is reduced, there will be two emerging effects, quantum confinement and surface effect, which dominate at nanoscale. Based on first-principles calculations, we demonstrate that due to an intriguing interplay between these two dominating effects, the topologica... | | 2012-01-01 |
42 |
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Scarpulla, Michael | Temperature dependent conductivity of polycrystalline Cu 2ZnSnS 4 thin films | The temperature-dependent conductivity of Cu2ZnSnS4 (CZTS) thin films prepared by sulfurization of different sputtered ZnS/Cu/Sn stacks and also of the same stack annealed for different times was investigated from 30-300 K. Fitting of the through-thickness conductivity requires a model including Mot... | | 2012-01-01 |
43 |
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Liu, Feng | Spatial and energy distribution of topological edge states in single Bi(111) bilayer | By combining scanning tunneling microscopy and spectroscopy, angle-resolved photoemission spectroscopy, and density functional theory band calculations, we directly observe and resolve the one-dimensional edge states of single bilayer (BL) Bi(111) islands on clean Bi2Te3 and Bi(111)-covered Bi2Te3 s... | | 2012-01-01 |
44 |
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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 |
45 |
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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 |
46 |
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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 |
47 |
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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 |
48 |
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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 |
49 |
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Liu, Feng | Quantum size effect on adatom surface diffusion | Using scanning tunneling microscopy, we demonstrate that the nucleation density of Fe islands on the surface of nanoscale Pb films oscillates with the film thickness, providing a direct manifestation of the quantum size effect on surface diffusion. The Fe adatom diffusion barriers were derived to be... | Quantum size effect; QSE; Adatoms; Surface diffusion; Fe islands; Nanoscale metallic structures; Epitaxial growth; Pb films | 2006-12 |
50 |
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Liu, Feng | Self-consistent tight-binding method | A self-consistent tight-binding formalism is described. The self-consistency is achieved by the introduction of a chemical hardness matrix and a generalization of the Huckel model to make the tight-binding Hamiltonian an implicit functional of the charge density. Studies of the band structures of d... | Tight-binding method; Self-consistency; Huckel model | 1995-10 |