Filters: Department: "Materials Science & Engineering" Collection: "ir_uspace" Format: "application/pdf"
| Creator | Title | Description | Subject | Date | ||
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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 | |
| 2 |
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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 | |
| 3 |
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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 | |
| 4 |
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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 | |
| 5 |
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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 | |
| 6 |
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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 | |
| 7 |
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Scarpulla, Michael | Pulsed laser induced ohmic back contact in CdTe solar cells | Creating an ohmic back contact has long been a problem for making efficient CdTe solar cells. Current devices utilize some combination of preferential chemical etching, buffer layer, and Cu doping with additional cost, time, and complexity added for each step. In this Letter, these processes are esc... | 2014-01-01 | |
| 8 |
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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 | |
| 9 |
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Tiwari, Ashutosh | Shape of the Hanle curve in spin-transport structures in the presence of an ac drive | Resistance between two ferromagnetic electrodes coupled to a normal channel depends on their relative magnetizations. The spin-dependent component, R, of the resistance changes with magnetic field, B, normal to the directions of magnetizations. In the field of spin transport, this change, R(B), orig... | 2014-01-01 | |
| 10 |
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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 | |
| 11 |
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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 | |
| 12 |
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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 | |
| 13 |
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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 | |
| 14 |
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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 | |
| 15 |
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Liu, Feng | Tuning nucleation density of metal island with charge doping of graphene substrate | We have demonstrated that the island nucleation in the initial stage of epitaxial thin film growth can be tuned by substrate surface charge doping. This charge effect was investigated using spin density functional theory calculation in Fe-deposition on graphene substrate as an example. It was found ... | 2014-01-01 | |
| 16 |
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Liu, Feng | Understanding graphene production by ionic surfactant exfoliation: a molecular dynamics simulation study | We have simulated sodium dodecyl sulfate (SDS) surfactant/waterþbilayer graphene mixture system to investigate two mechanisms of graphene exfoliation: changing the interlayer distance and sliding away the relative distance. By calculating the total energy as a function of the interlayer (sliding-aw... | 2014-01-01 | |
| 17 |
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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 | |
| 18 |
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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 | |
| 19 |
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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 | |
| 20 |
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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 | |
| 21 |
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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 | |
| 22 |
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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 | |
| 23 |
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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 | |
| 24 |
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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 | |
| 25 |
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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 |