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" Applications of Liquid Phase Epitaxy in Optoelectronic Devices "
Xin Zhao
Woodall, Jerry M.
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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804233
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| Doc. No
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TL49055
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| Call number
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1845292203; 10165853
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| Main Entry
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Islam, A.S.M. Faridul
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| Title & Author
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Applications of Liquid Phase Epitaxy in Optoelectronic Devices\ Xin ZhaoWoodall, Jerry M.
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| College
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University of California, Davis
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| Date
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2016
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| Degree
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Ph.D.
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| field of study
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Electrical and Computer Engineering
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2016
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| Page No
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89
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| Note
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Committee members: Hihath, Joshua; Islam, M. Saif
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| Note
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Place of publication: United States, Ann Arbor; ISBN=978-1-369-20229-8
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| Abstract
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Liquid phase epitaxy is a technique to grow high purity semiconductor crystals from a melt. This work explored applications of liquid phase epitaxy in two optical devices – solar cells and light emitting diodes. For the solar cell application, liquid phase epitaxy was used to optimize the efficiency of Al<sub>0.2</sub>Ga<sub>0.8</sub>As solar cells. Al<sub>0.2</sub>Ga<sub> 0.8</sub>As is the preferred material for the top sub-cell of a dual-junction solar cell based on an efficient crystalline silicon bottom sub-cell. Preliminary studies of Al<sub>0.2</sub>Ga<sub>0.8</sub>As epilayers grown by liquid phase epitaxy, including photo-luminescent and Hall effect studies, indicated that the material was of high quality in terms of both carrier lifetimes and mobility. Then three approaches of growing AlGaAs solar cells on GaAs substrates were experimented, among which an approach was identified as being suitable for producing efficient AlGaAs solar cells. The approach involves growing an n-type AlGaAs base first, followed by an isothermal Zn diffusion process to form the p-type AlGaAs emitter and the window layer. The approach also requires that the substrate be always protected by a thin layer of residual melt throughout the growth to prevent interface or surface oxidation, and that the window layer be subsequently removed by buffer oxide etch solution. An open-circuit voltage of 1.15 V and an efficiency of 6.56% was observed from our cell without anti-reflective coatings. For the light emitting diode application, liquid phase epitaxy was used to grow lattice-mismatched GaInP epilayers on GaP substrates. Layered growth of Ga<sub>x</sub>In<sub>1-x</sub>P on GaP was achieved when the lattice mismatch exceeds 0.4% (x<0.95) using a Sn-based melt. Compositional control was observed by (1) changing the cooling rate and (2) varying the melt-back temperature at the beginning of the growth.
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| Subject
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Electrical engineering
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| Descriptor
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Applied sciences;AlGaAs solar cells;Liquid phase epitaxy;Optoelectronic devices
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| Added Entry
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Woodall, Jerry M.
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Electrical and Computer EngineeringUniversity of California, Davis
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