Photoluminescence of Single Quantum Well Structures in Gallium Arsenide PDF Download
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Author: Christian A. Bartholomew
Publisher:
ISBN: 9781423528197
Category : Beryllium
Languages : en
Pages : 76
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Book Description
The continued development of state-of the-art semiconductor technologies and devices by the United States Air Force and the Department of Defense requires accurate and efficient techniques to evaluate and model these new materials. Of particular interest to the Air Force are quantum well structures which can be used for small-scale laser sources in fly-by-light applications, as efficient infrared countermeasures to heat-seeking missiles, or as advanced seekers in optically guided missiles. This thesis provides the initial experimental procedures and data necessary to begin producing accurate yet robust models. Although carrier effective masses could not be evaluated using hot-electron photoluminescence, photoluminescence excitation and temperature studies were conducted to determine the effects of strain and impurities on band structure in quantum structures. Beryllium-doped indium gallium arsenide (InGaAs:Be) quantum wells, compressively strained to lattice- match gallium arsenide, were studied, and parameters for strained energy gap, heavy hole-light hole split, and acceptor binding energy were evaluated. With the carrier effective masses fixed at accepted values, strain produced a 1.2715 eV energy gap within the well and a heavy hole-light hole split of 23.2meV. Finally, the beryllium binding energy was found to be 22.1 meV measured above the highest valence band (first quantized heavy hole band) at 300 K.
Author: Christian A. Bartholomew
Publisher:
ISBN: 9781423528197
Category : Beryllium
Languages : en
Pages : 76
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Book Description
The continued development of state-of the-art semiconductor technologies and devices by the United States Air Force and the Department of Defense requires accurate and efficient techniques to evaluate and model these new materials. Of particular interest to the Air Force are quantum well structures which can be used for small-scale laser sources in fly-by-light applications, as efficient infrared countermeasures to heat-seeking missiles, or as advanced seekers in optically guided missiles. This thesis provides the initial experimental procedures and data necessary to begin producing accurate yet robust models. Although carrier effective masses could not be evaluated using hot-electron photoluminescence, photoluminescence excitation and temperature studies were conducted to determine the effects of strain and impurities on band structure in quantum structures. Beryllium-doped indium gallium arsenide (InGaAs:Be) quantum wells, compressively strained to lattice- match gallium arsenide, were studied, and parameters for strained energy gap, heavy hole-light hole split, and acceptor binding energy were evaluated. With the carrier effective masses fixed at accepted values, strain produced a 1.2715 eV energy gap within the well and a heavy hole-light hole split of 23.2meV. Finally, the beryllium binding energy was found to be 22.1 meV measured above the highest valence band (first quantized heavy hole band) at 300 K.
Author: Christopher Owen John Griffiths
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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 quantum structures because the exciton population responsible for the measured luminescence is sensitive to well width, alloy composition, strain (in lattice-mismatched structures), and interface roughness. Continuous wave (cw) and time-resolved photoluminescence, and photoluminescence excitation (PLE) measurements were used to gain insight into the physics of GaAs alloy quantum structures. The strain study in Chapter 4 measured the strain in individual quantum wells (within In$sb{rm x}$Ga$sb{rm 1-x}$As/GaAs multiquantum well samples) by analyzing excitonic luminescence as a function of incident laser energy. These results led to the equilibrium strain model which describes strain due to lattice-mismatch being shared between well and barrier layers in strain-relaxed multiquantum well structures. The small feature study of Chapter 5 investigates the presence of an absorption dip in the photoluminescence spectra of an In$sb{0.10}$Ga$sb{0.90}$As single quantum well and five quantum well sample. The dip is explained by fast relaxation of mobile excitons from the barrier material into the quantum well layer. Chapter 6 investigates the effect of interface roughness on tunneling times between narrow well and wide well in Al$sb{rm x}$Ga$sb{rm 1-x}$As/GaAs asymmetric coupled quantum well structures.
Author: Toni D. Sauncy
Publisher:
ISBN:
Category : Gallium arsenide semiconductors
Languages : en
Pages : 344
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Book Description
Author: Ikegami
Publisher: CRC Press
ISBN: 9780750302500
Category : Technology & Engineering
Languages : en
Pages : 1002
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Book Description
Bringing together international experts from 16 countries, Gallium Arsenide and Related Compounds 1992 focuses on device applications for Gallium Arsenide and related compounds. A topic of importance discussed is the first GaAs supercomputer from Fujitsu. The book also explores carbon doping and device applications in laser diodes, light modulators, and amplifiers, emphasizing business opportunity in consumer applications such as personal communications and TV tuners. It includes an account of the use of scanning tunneling microscopies in GaAs and related compounds. This book is ideal for physicists, materials scientists, and electronics and electrical engineers involved in III-V compound research.
Author: Linda Jean Blue
Publisher:
ISBN:
Category : Quantum wells
Languages : en
Pages : 282
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Book Description
Author: Anup Pancholi
Publisher: ProQuest
ISBN: 9780549924562
Category : Gallium arsenide
Languages : en
Pages :
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Book Description
The last few years have seen rapid advances in nanoscience and nanotechnology, allowing unprecedented manipulation of nanostructures controlling solar energy capture, conversion, and storage. Quantum confined nanostructures, such as quantum wells (QWs) and quantum dots (QDs) have been projected as potential candidates for the implementation of some high efficiency photovoltaic device concepts, including the intermediate band solar cell (IBSC). In this dissertation research, we investigated multiple inter-related themes, with the main objective of providing a deeper understanding of the physical and optical properties of QD structures relevant to the IBSC concept. These themes are: (i) Quantum engineering and control of energy levels in QDs, via a detailed study of the electronic coupling in multilayer QD structures; (ii) Controlled synthesis of well-organized, good quality, high volume density, and uniform-size QD arrays, in order to maximize the absorption efficiency and to ensure the coupling between the dots and the formation of the minibands; and (iii) Characterization of carrier dynamics and development of techniques to enhance the charge transport and efficient light harvesting. A major issue in a QD-based IBSC is the occurrence of charge trapping, followed by recombination in the dots, which results in fewer carriers being collected and hence low quantum efficiency. In order to collect most of the light-generated carriers, long radiative lifetimes, higher mobilities, and a lower probability of non-radiative recombination events in the solar cell would be desirable. QD size-dependent radiative lifetime and electronic coupling in multilayer QD structures were studied using photoluminescence (PL) and time-resolved photoluminescence (TRPL). For the uncoupled QD structures with thick barriers between the adjacent QD layers, the radiative lifetime was found to increase with the QD size, which was attributed to increased oscillator strength in smaller size dots. On the other hand, in the sample with thin barrier and electronically coupled QDs, the radiative lifetime increases and later decreases with the dot size. This is due to the enhancement of the oscillator strength in the larger size, coherently coupled QDs. In order to improve the quality of multi-layer QD structures, strain compensated barriers were introduced between the QD layers grown on off-oriented GaAs (311)B substrate. The QD shape anisotropy resulted from the growth on off-oriented substrate was studied using polarization-dependent PL measurements both on the surface and the edge of the samples. The transverse electric mode of the edge-emitted PL showed about 5° deviation from the sample surface for the dots grown on (311)B GaAs, which was attributed to the tilted vertical alignment and the shape asymmetry of dots resulted from the substrate orientation. Significant structural quality improvements were attained by introducing strain compensated barriers, i.e., reduction of misfit dislocations and uniform dot size formation. Longer lifetime (~1 ns) and enhanced PL intensity at room temperature were obtained, compared to those in conventional multilayer (In, Ga)As/GaAs QD structures. A significant increase in the open circuit voltage (V oc) was observed for the solar cell devices fabricated with the strain compensated structures. A major issue in a QD IBSC is the occurrence of charge trapping, followed by recombination in the dots, which results in fewer carriers being collected, and hence low quantum efficiency. We proposed and studied a novel structure, in which InAs QDs were sandwiched between GaAsSb (12% Sb) strain-reducing layers (SRLs) with various thicknesses. Both short (~1 ns) and long (~4-6 ns) radiative lifetimes were measured in the dots and were attributed to type-I and type-II transitions, respectively, which were induced by the band alignment modifications at the QD/barrier interface in the structures analyzed, due to the quantum confinement effect resulting from different GaAsSb barrier thicknesses. Based on our findings, a structure with type-II QD/barrier interface with relatively long radiative recombination lifetime may be a viable candidate in designing IBSC.
Author: Günter Weimann
Publisher: CRC Press
ISBN: 9780750302951
Category : Technology & Engineering
Languages : en
Pages : 880
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Book Description
Gallium Arsenide and Related Compounds 1993 covers III-V compounds from crystal growth of materials to their device applications. Focusing on the fields of optical communications and satellite broadcasting, the book describes the practical applications for GaAs and III-V compounds in devices and circuits, both conventional and those based on quantum effects. It also discusses ultrafast GaAs transistors and integrated circuits, novel laser diodes, and tunneling devices, and considers the direction for future technologies. In addition, this volume addresses the increasing demands of ultra high speed systems that require careful selection of III-V materials to optimize the performance of electronic and optoelectronic components. It is ideal reading for physicists, materials scientists, electrical, and electronics engineers investigating III-V compound materials, properties, and devices.
Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 584
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Book Description
Author: Sue-chu Shen
Publisher: World Scientific
ISBN: 9813201436
Category :
Languages : en
Pages : 394
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Book Description
This volume contains important and active results in the fields of Superlattices and Quantum Wells. It includes current prospects regarding scientific discoveries and future device applications. Papers are contributed by leading scientists in the world.
Author:
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages : 2002
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Book Description
