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Full-Text Articles in Condensed Matter Physics
Electrical And Optical Characterization Of Two-Dimensional Semiconductors Using Ultrafast Spectroscopy, Pan Adhikari
Electrical And Optical Characterization Of Two-Dimensional Semiconductors Using Ultrafast Spectroscopy, Pan Adhikari
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The emergence of two-dimensional (2D) layered materials provides unprecedented opportunities for studying excitonic physics due to the strong Coulomb interaction between the electron-hole pair. Because of the reduced dimensionality and weak dielectric screening, the exciton is stable at room temperature, unlike bulk semiconductors. The evolution from low to high carrier density for optical gain in 2D semiconductors involves insulating exciton gas, exciton condensation, co-existence of various excitonic complexes, electron-hole plasmas (EHPs), or electron-hole liquids (EHLs), leading to the Mott transition. Strong interaction among the excitons, such as exciton-exciton annihilation (EEA), serves as a hot-carrier generation. A bound exciton dissociates into …
In Situ Study Of Ultrafast Carrier Transport Dynamics In Perovskite Thin-Films, Kanishka Kobbekaduwa
In Situ Study Of Ultrafast Carrier Transport Dynamics In Perovskite Thin-Films, Kanishka Kobbekaduwa
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Perovskites are a novel class of materials that have piqued the interest of researchers in photovoltaics, photodetectors, and optoelectronics. In this study, we measure and elucidate in situ ultrafast carrier dynamics in both organic and inorganic, lead, and non-lead-based halide perovskite thin films using ultrafast photocurrent spectroscopy (UPCS) with a sub-25 ps time resolution. The UPCS technique enables us to define carrier transport dynamics in spatial, temporal, and energy landscapes via measurements at different electric fields, laser intensities, and temperatures. Here we explore and analyze solution-processed bulk MAPbI3 and nanocrystalline CsPbI3-based devices and novel non-lead double-layered perovskite …
Quantum-Mechanical Evaluation Of Defects In Uranium-Bearing Materials, Megan Hoover
Quantum-Mechanical Evaluation Of Defects In Uranium-Bearing Materials, Megan Hoover
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Quantum-mechanical calculations using density functional theory with the generalized gradient approximation were employed to investigate the effects dopants have on the uranium dioxide (UO2) structure. Uraninite is a common U4+ mineral in the Earth's crust and an important material used to produce energy and medical isotopes. Though the incorporation mechanism remains unclear, divalent cations are known to incorporate into the uranium dioxide system. Three charge-balancing mechanisms were evaluated to achieve a net neutral system, including the substitution of (1) a divalent cation for a tetravalent uranium atom and oxygen atom; (2) two divalent cations for a tetravalent …