Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 71 for “"Carrier dynamics"”.
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Carrier Dynamics in Perovskite Nanocrystals
… for high-efficiency solar cells. Ultrafast carrier-phonon interactions in semiconductors represent a major loss of the excess energy of photoexcitations above the bandgap. We demonstrate approaches to suppress the relaxation process, which may allow the full photon energy to be usefully …
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Femtosecond carrier dynamics in AlGaAs
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1994.
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Charge carrier dynamics in lead sulfide quantum dot solids
… reduced energetic disorder on increasing charge carrier hopping rates. In Chapter 3, we present temperature-dependent transport measurements that demonstrate again that when energetic disorder is very low, structural changes will dominate the dynamics. We find increasing mobility with decreasing …
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Carrier dynamics of ErAs:GaBixAs1-x using infrared pump, terahertz probe spectroscopy.
… these components leads to competing pathways for carrier relaxation. While carrier dynamics in GaBiAs and ErAs:GaAs have been studied extensively, dynamics in the composite material ErAs:GaBiAs, with both ErAs and GaBiAs components, remain largely unexplored. This dissertation investigates the …
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Charge Carrier Dynamics of Lead Halide Perovskites Probed with Ultrafast Spectroscopy
… this thesis, we investigate the nature of charge carrier generation, relaxation and recombination in a range of lead halide perovskites. We focus on understanding whether the photophysical behaviour of these perovskite materials is like that of highly-ordered inorganic crystalline semiconductors …
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The Effect of Morphology on Carrier Dynamics in Solution Processed Solar Cells
<p>This dissertation looks at the charge transport properties of solution processed solar cells and how these properties are effected by the microstructure and morphology of the material. It begins with an introduction and history of the field of solution processed solar cells, focusing on organic …
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Improving charge carrier dynamics in tin (II) sulfide through targeted defect engineering
… for commercial production. Low minority carrier lifetimes of <100 ps have been shown to be the root cause of this low performance, and carrier lifetimes >1 ns are predicted to enable >10%-efficient devices. In this thesis work, I employed defect modeling to identify the most …
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Investigation of carrier dynamics in InN, InGaN, and GaAsBi by optical pump-probe techniques /
The thesis is dedicated to investigation of carrier dynamics in InN, InGaN, and GaAsBi heterostructures by using light-induced transient gratings and differential transmission techniques. The experimental studies in a wide range of excess carrier densities and temperatures revealed that …
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Study of ultrafast polarization and carrier dynamics in semiconductor nanostructures : a THz spectroscopy approach
In this work the ultrafast polarization and carrier dynamics in semíconductor nanostructures is studied using THz emission and optical-pump THz probe spectroscopy. A theoretical model of dynamical screening of an optically excited biased quantum well is developed.
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Interface roughness mediated optical decay and carrier dynamics in type II AlAs/GaAs heterostructures
… been known to be an important factor determining carrier mobility in short period wells. Interface roughness (IR) has also been suggested as a possible decay mechanism in type II AlAs/GaAs heterostructures. Photoluminescence (PL) has been the primary tool used to study type II AlAs/GaAs …
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Ultrafast carrier dynamics and enhanced electroabsorption in (gallium,indium)arsenide/(aluminum,indium)arsenide asymmetric double quantum well structures
… A single time constant is observed at low carrier densities indicating the holes tunnel from the narrow well (NW) to the wide well (WW) at least as fast as electrons. At high carrier densities a two component decay is observed, consistent with phase-space filling and space-charge effects …
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Exploring charge carrier dynamics in quantum dot and double heterojunction nanorod light emitting devices using transient electroluminesence measurements
… and concentration of the different charge carriers residing in the emitting layer. There are still open debates in the quantum dot light emitting diode (QD-LED) community regarding the details of the charge carrier populations which are expected to influence efficiency droop at higher …
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Photoluminescence studies of carrier dynamics in (indium(x),aluminum(x)) gallium(1-x) arsenic/gallium arsenide quantum well structures
This thesis discusses carrier dynamics of III-V semiconductor quantum well structures probed by photoluminescence techniques in In$\sb{\rm x}$Ga$\sb{\rm 1-x}$As/GaAs and Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As/GaAs quantum well systems. Photoluminescence is a useful nondestructive probe of direct-gap …
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Spectroscopic Studies on the Impact of Defects in Hybrid Organic-Inorganic Perovskites on Charge Carrier Dynamics and Photovoltaic Device Performance
… the spectroscopic characterization of charge carriers in methylammonium lead iodide and the use of this characterization, along with time-resolved spectroscopy, to better understand the influence of carrier dynamics on solar cell device performance. We observed that a decrease in device fill …
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Dynamics of Energy Carriers in Solids During Interaction with Ultrafast Laser Pulses
<p>The dynamics of energy carriers, including mainly electrons, holes, and phonons, determine important physical properties of solids such as thermal conductivity and electrical conductivity, which affect the design and the performance of solid-state devices. Solids can be classified as metal, …
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Charge Carrier Localisation in Metal Halide Perovskites for Optoelectronic Applications
This dissertation is concerned with the charge carrier dynamics in semiconductors based on metal-halide perovskites. These materials have shown remarkable performance in optoelectronic applications like solar cells or light-emitting devices. They are solution-processable at low temperature using …
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Charge carrier transport and recombination in semiconductors: Insights from statistical analysis and machine learning techniques
… thesis pioneers techniques to understand charge carrier dynamics in semiconductor materials, with the goal of advancing next–generation optoelectronic devices, with three main thrusts explored. In Chapter 4, efficient exciton energy transport in thin Ruddlesden-Popper perovskite flakes is …
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Resonant Raman scattering studies of III-V semiconductor microstructures
… lattice structural information and by probing carrier dynamics both directly and via the electron-phonon interaction. We have examined three physical systems accentuating three aspects of Raman utility. Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As alloy work emphasizes electronic behavior, migration …
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High-speed characterizations of single quantum-well transistor laser
… development and device structure, as well as the carrier dynamics in the TL will be first presented to provide background discussion. The focus of this thesis will be on the methods of high-speed characterizations on TLs and data of the optical modulation bandwidth, f-3dB, and error-free data …
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