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Showing 1 to 20 of 79 for “"carrier lifetime"”.
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Physical modeling of base carrier lifetime and frequency response of heterojunction bipolar transistor
… is to assess the concentration of base minority carrier captured in the QW and give an analytical expression for the carrier lifetime in the base, which is a key factor for device frequency performance. Expressions for the physical parameters such as capture time, base recombination lifetime and …
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Defects and charge-carrier lifetime in early-stage photovoltaic materials : relating experiment to theory
… solar cell efficiency due to short charge-carrier lifetimes. In this thesis, such defects and their impact on lifetime in early-stage PV materials are investigated, focusing on experimental methods to assess lifetime connected to theoretical concepts about both defects and lifetime …
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Photoconductivity and minority carrier lifetime in tin sulfide and gallium arsenide semiconductors for photovoltaics
… program (SCAPS), improvements in the minority-carrier lifetime of cell materials show not only significant improvements in cell efficiencies, but also an un-masking of improvements by other properties, which are inhibited when the lifetime is too short. This work aims to calculate the …
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Empirical correlation of minority carrier lifetime to detect density profile in germanium on silicon heteroepitaxy
… by dopants. Using the effective minority carrier lifetime measured as a function of Ge film thickness, an empirical correlation is established between the minority carrier lifetime and the defect density in the Ge film as a function of distance from the Ge/Si interface and relating the …
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Photoluminescence Spectra and Carrier Lifetime Measurements in Cadmium Selenide, Gallium Arsenide and Gallium - Arsenide(1-X) - Phosphide(x)
Made available in DSpace on 2014-12-10T19:06:38Z (GMT). No. of bitstreams: 1 7114826.pdf: 3009405 bytes, checksum: fcd9c2de26664cbb7ca797d09fe6c0a8 (MD5) Previous issue date: 1970
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Purity matters : enhancing carrier transport properties in tin sulfide for photovoltaic applications by reducing impurity content
… photovoltaic applications, is hampered by poor carrier-transport properties, particularly minority-carrier lifetime. This study investigates the role of intrinsic and extrinsic crystallographic point defects on the electronic transport properties of SnS. High-purity SnS is grown via …
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GaN sensorių optinio ir elektrinio atsako charakteristikų tyrimas /
… response dependence on neutron fluences. Excess carrier lifetime is one of the most important material parameters which is directly related with material defects. Therefore, carrier lifetime ascribed to radiative and non-radiative recombination has been examined by combining time-resolved …
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Advanced Characterization of Defects in Silicon Wafers and Solar Cells
… of bulk defects in silicon. Injection dependent lifetime spectroscopy, a technique characterizes defects from the measured charge carrier lifetime, is the main technique investigated and ameliorated in this thesis. However, other techniques are also applied together with injection dependent …
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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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Structural defect engineering of tin (II) sulfide thin films for photovoltaics
… maximum of 32%, primarily due to a low minority-carrier lifetime. In this work, I assess the impact of structural defects and anisotropy on the minority-carrier lifetime and other key device parameters, shedding light on the path to high-efficiency SnS-based photovoltaics. SnS thin films are …
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Carrier transport properties measurements in wide bandgap materials
This dissertation examines the carrier transport properties, diffusion length, effective carrier lifetime, and resistivity in two wide bandgap materials, GaN and diamond. A combination of two methods was used to obtain these transport properties. The two were optical beam induced current (OBIC) and …
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Temperature-Dependent High-Speed Modulation and Wavelength Conversion Using Quantum-Well Lasers
… theoretical fits to the data and predicted carrier densities are obtained using a many-body gain model. The modulation response due to optical pumping at 1.3 mum wavelength is compared with the electrical response in order to remove the influence of electrical parasitics. The temperature …
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Co-optimizing silicon solar cell processing for efficiency and throughput
… optimizations typically maximize minority carrier lifetime without constraining process time and device parameters. This thesis explores a novel phosphorus diffusion process in which there are no isothermal steps. The goal of this work is to demonstrate simultaneous maximization of …
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Defect investigations in InAs/GaSb type-II strained layer superlattice
… faces several challenges, including low minority carrier lifetime, resulting from trap levels that cause Schockley-Read-Hall recombination. These low lifetimes lead to reduced signal-to-noise ratio and higher dark current. Therefore, increasing the lifetime is important for improving this …
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Characterisation of radiation effects in ultra-thin GaAs solar cells for space applications
… ultra-thin solar cells can be attributed to the carrier lifetime remaining greater than the time taken for carriers to traverse the absorber layer, even after the lifetime is degraded severely by radiation damage. The eventual collapse in short-circuit current beyond 2 × 10¹³ MeV g⁻¹ is found to …
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Retrograde melting in transition metal-silicon systems : thermodynamic modeling, experimental verification, and potential application
… melting to improve the electronic minority carrier lifetime of low quality silicon solar cell materials is considered.
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Characteristics, Theory and Modeling of the Transistor Laser
… characteristics of fast base spontaneous carrier lifetime, high differential optical gain, and unique three-terminal electrical-optical characteristics for direct “read-out” of its optical properties. These potentially lead to advantageous and useful features for designing high-speed …
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Characterization and modeling of CdCl2 treated CdTe/CdS thin-film solar cells
… was reduced despite an increase in minority carrier lifetime values. The mechanism of reduced performance is suggested to be the formation of a low bandgap CdTe layer resulting from sulfur diffusion from the CdS layer. Sulfur diffusion primarily occurs during the CdCl2 treatment and also …
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Developing high efficiency Cu2ZnSnS4 (CZTS) thin film solar cells by sputtering
… the electrical property of CZTS film such as carrier concentration and minority carrier lifetime, thereby influencing the CZTS solar cell efficiency. Secondly, the effects of sulfurization annealing atmosphere and post-heat treatment have been studied. The “epitaxial” CdS/CZTS interface and …
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Quantitative Carrier Transport in Quantum Dot Photovoltaic Solar Cells from Novel Photocarrier Radiometry and Lock-in Carrierography
… significantly, due to the not-well-understood carrier transport mechanisms and the lack of effective characterization techniques. Addressing these issues, carrier transport kinetics in CQD systems were studied to develop high-frequency dynamic testing and/or large-area quantitative imaging …
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