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 30 for “"carrier diffusion"”.
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Microscale Energy Transport in Lead Halide Perovskites
… microscale, and develop a framework to quantify carrier diffusion anisotropy and grain boundary effects in optical microscopy measurements. First, we quantify the enhancement due to photon recycling in the macroscale for state-of-the-art perovskite films. We find that even with finite …
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Developing cuprous oxide thin film characterization techniques to illuminate efficiency-limiting mechanisms in photovoltaic applications
… carrying energy in excess of 2.6 eV. Majority carrier mobility is measured as 58.1 cm²/V·s, approaching the levels of monocrystalline oxidized films in literature. These high mobilities indicate that with carrier lifetime >10 nanoseconds, minority carrier diffusion length could easily exceed …
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Characterization of, and novel architectures for, strained-layer superlattice infrared photodetectors
… is important to characterize and understand the carrier dynamics of T2SLs. The primary thrust of this thesis is the description and development of experimental techniques for characterizing T2SL detectors. The first part of this dissertation focuses on establishing a new approach to electron beam …
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A compact model for silicon controlled rectifiers in low voltage CMOS processes
… of electric fields in the well region on carrier diffusion between the anode and cathode. Further, a detailed validation of the compact model is presented. A methodology for parameter extraction is also discussed.
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Defect characterization of antimonide-based type-II superlattices for infrared detection
… materials, known as a superlattice (SL), the carriers form minibands that have an effective band gap lower than that of the constituent materials and suited for MWIR and LWIR applications. Traditionally, InAs/GaSb has been the preferred material system for T2SL IR detectors, but recent work …
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Data-driven approach to understanding exciton-exciton interactions in CsPbBr₃ nanocrystals
… a number of desirable properties such as long carrier diffusion lengths and defect tolerance that arise from the materials' unique dielectric properties. Although much of the initial interest in lead halide perovskites was geared towards producing highly efficient solar cells from the bulk …
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Three Grains, Two Photons and a Colourful Diamond
… suppress it. We then unveil buried charge-carrier recombination pathways in both thin film and micro-crystal methylammonium lead halide perovskite structures through 3D photoluminescence tomography acquired using two-photon confocal microscopy. These measurements reveal that light-induced …
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Nanostructured photovoltaics : improving device efficiency and measuring carrier transport
… addition of the ZnO nanowire array and improved carrier collection due to the bulk heterojunction effect. Furthermore, electron beam-induced current (EBIC) was used to study charge transport in PbS QD films. It is shown that holes are the minority carrier in PbS QD films treated with …
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Zero-field time-of-flight characterization of minority carrier transport in heavily carbon-doped gallium arsenide and indium gallium arsenide
… and in AlGaAs/GaAs HBT reliability. Minority carrier electron diffusion coefficients and lifetimes have been measured in heavily doped p-type GaAs and In$\sb{0.53}$G$\sb{0.47}$As using the zero-field time-of-flight (ZFTOF) technique in structures that simulate the base transport in HBTs. To …
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Laser beam induced current studies of Hg1-xCdxTe photodiodes
… of the LBIC problem using the full drift-diffusion and φ,ψ treatment of an n-on-p photodiode together with supporting experimental measurements have revealed a wealth of hidden physical mechanisms, quantifiable relationships, and conditions with which to characterize the p-n junction. A …
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Defect engineering of cuprous oxide thin-films for photovoltaic applications
… nanowire array to overcome the short minority carrier diffusion length in Cu₂O. A scalable fabrication process is developed using colloidal lithography and hydrothermal growth of ZnO nanowires. Optical simulations are also conducted to investigate the effect of nanostructured device geometry on …
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Approaching Novel Perovskites Photovoltaic Devices through Machine Learning and Interfacial Engineering
… light absorption coefficient, relatively long carrier diffusion length, and carrier recombination lifetime [6-9]. However, even with an increasing number of studies carried out, perovskite solar cell is still facing plenty of challenges towards commercialization. Two main challenges towards …
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Toward a User's Toolkit for Modeling Scintillator Nonproportionality and Light Yield
… term. The main physical phenomena involved are carrier diffusion, trapping, drift in internal electric fields, and nonlinear rates of radiative and nonradiative recombination. Some complexity is added by the now well-established fact that the electron temperature is changing during important …
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CMOS passive pixel image design techniques
… current composed of optically-generated carrier diffusion, blooming and subthreshold currents contaminates the pixel output. This parasitic current is detrimental to the imager because a few bright pixels can affect the rest of the pixels on the column line, resulting in bright vertical …
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Coupled Rate and Transport Equations Modeling Light Yield, Pulse Shape, and Proportionality to Energy in Electron Tracks: A Study of CsI and CsI:Tl Scintillators
… linear and nonlinear interactions of the charge carriers deposited along the ionization track. The tracks are initially very narrow before hot and thermalized carrier diffusion takes effect. This suggests that an adequate and computationally manageable representation may be obtained by modeling …
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Near Field Scanning Optical Microscopy (NSOM) of nano devices
… of transport parameters, such as minority carrier mobility and diffusion length that are vital to the performance of optoelectronic devices. The work involves the development of a unique nano-scale imaging technique applicable to a wide range of structures. The main structures of interest …
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Microstructured Halide Perovskites for Energy Applications
… 109- 1010 cm−3), along with very high charge carrier diffusion lengths. However, single crystals require growth in extremely thin layers to prevent charge recombination within the bulk, and careful attention to surface quality, where structural defects often form traps. A key strategy to …
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Towards High-Performance Multi-Junction Perovskite Solar Cells: Fabrication, Interlayer Design, and Characterisation
… including high absorption coefficients, long carrier diffusion lengths, and tuneable bandgaps, have driven remarkable progress, particularly in the field of photovoltaics. Metal halide perovskites are particularly attractive for multi-junction photovoltaics because their bandgaps can be finely …
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Properties and Processing of Chalcogenide Perovskites
… properties, including absorption coefficients, carrier mobilities, and carrier diffusion lengths. High-quality thin film samples of chalcogenide perovskites will enable measurements of these properties. This thesis has two main goals: 1) to further investigate and characterize bulk properties of …
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Theory and Experiment of Antimony-Based Type-Ii Superlattice Infrared Photodetectors
… and transport parameters (e.g., minority carrier diffusion length) obtained by electron beam induced current (EBIC) technique. By successfully modeling the QE of InAs/GaSb superlattice photodiodes, we ensure that the depletion region in InAs/GaSb superlattice photodiodes is effective in …
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