Structural and Optical Properties of III-V Semiconductor Materials for Photovoltaics and Power Electronic Applications

abstract: This dissertation focuses on the structural and optical properties of III-V semiconductor materials. Transmission electron microscopy and atomic force microscopy are used to study at the nanometer scale, the structural properties of defects, interfaces, and surfaces. A correlation with opt...

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Other Authors: SU, PO-YI (Author)
Format: Doctoral Thesis
Language:English
Published: 2020
Subjects:
Online Access:http://hdl.handle.net/2286/R.I.62663
id ndltd-asu.edu-item-62663
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spelling ndltd-asu.edu-item-626632020-12-09T05:00:36Z Structural and Optical Properties of III-V Semiconductor Materials for Photovoltaics and Power Electronic Applications abstract: This dissertation focuses on the structural and optical properties of III-V semiconductor materials. Transmission electron microscopy and atomic force microscopy are used to study at the nanometer scale, the structural properties of defects, interfaces, and surfaces. A correlation with optical properties has been performed using cathodoluminescence. The dissertation consists of four parts. The first part focuses on InAs quantum dots (QDs) embedded in a GaInP matrix for applications into intermediate band solar cells. The CuPt ordering of the group-III elements in Ga0.5In0.5P has been found to vary during growth of InAs QDs capped with GaAs. The degree of ordering depends on the deposition time of the QDs and on the thickness of the capping layer. The results indicate that disordered GaInP occurs in the presence of excess indium at the growth front. The second part focuses on the effects of low-angle off-axis GaN substrate orientation and growth rates on the surface morphology of Mg-doped GaN epilayers. Mg doping produces periodic steps and a tendency to cover pinholes associated with threading dislocations. With increasing miscut angle, the steps are observed to increase in height from single to double basal planes, with the coexistence of surfaces with different inclinations. The structural properties are correlated with the electronic properties of GaN epilayers, indicating step bunching reduces the p-type doping efficiency. It is also found that the slower growth rates can enhance step-flow growth and suppress step bunching. The third part focuses on the effects of inductively-coupled plasma etching on GaN epilayers. The results show that ion energy rather than ion density plays the key role in the etching process, in terms of structural and optical properties of the GaN films. Cathodoluminescence depth-profiling indicates that the band-edge emission of etched GaN is significantly quenched. The fourth part focuses on growth of Mg-doped GaN on trench patterns. Anisotropic growth and nonuniform acceptor incorporation in p-GaN films have been observed. The results indicate that growth along the sidewall has a faster growth rate and therefore a lower acceptor incorporation efficiency, compared to the region grown on the basal plane. Dissertation/Thesis SU, PO-YI (Author) Ponce, Fernando A (Advisor) Smith, David J (Committee member) Crozier, Peter A (Committee member) Zhao, Yuji (Committee member) Arizona State University (Publisher) Engineering Characterization III-V Semiconductors Intermediate Band Solar Cells Power Electronics eng 127 pages Doctoral Dissertation Materials Science and Engineering 2020 Doctoral Dissertation http://hdl.handle.net/2286/R.I.62663 http://rightsstatements.org/vocab/InC/1.0/ 2020
collection NDLTD
language English
format Doctoral Thesis
sources NDLTD
topic Engineering
Characterization
III-V Semiconductors
Intermediate Band Solar Cells
Power Electronics
spellingShingle Engineering
Characterization
III-V Semiconductors
Intermediate Band Solar Cells
Power Electronics
Structural and Optical Properties of III-V Semiconductor Materials for Photovoltaics and Power Electronic Applications
description abstract: This dissertation focuses on the structural and optical properties of III-V semiconductor materials. Transmission electron microscopy and atomic force microscopy are used to study at the nanometer scale, the structural properties of defects, interfaces, and surfaces. A correlation with optical properties has been performed using cathodoluminescence. The dissertation consists of four parts. The first part focuses on InAs quantum dots (QDs) embedded in a GaInP matrix for applications into intermediate band solar cells. The CuPt ordering of the group-III elements in Ga0.5In0.5P has been found to vary during growth of InAs QDs capped with GaAs. The degree of ordering depends on the deposition time of the QDs and on the thickness of the capping layer. The results indicate that disordered GaInP occurs in the presence of excess indium at the growth front. The second part focuses on the effects of low-angle off-axis GaN substrate orientation and growth rates on the surface morphology of Mg-doped GaN epilayers. Mg doping produces periodic steps and a tendency to cover pinholes associated with threading dislocations. With increasing miscut angle, the steps are observed to increase in height from single to double basal planes, with the coexistence of surfaces with different inclinations. The structural properties are correlated with the electronic properties of GaN epilayers, indicating step bunching reduces the p-type doping efficiency. It is also found that the slower growth rates can enhance step-flow growth and suppress step bunching. The third part focuses on the effects of inductively-coupled plasma etching on GaN epilayers. The results show that ion energy rather than ion density plays the key role in the etching process, in terms of structural and optical properties of the GaN films. Cathodoluminescence depth-profiling indicates that the band-edge emission of etched GaN is significantly quenched. The fourth part focuses on growth of Mg-doped GaN on trench patterns. Anisotropic growth and nonuniform acceptor incorporation in p-GaN films have been observed. The results indicate that growth along the sidewall has a faster growth rate and therefore a lower acceptor incorporation efficiency, compared to the region grown on the basal plane. === Dissertation/Thesis === Doctoral Dissertation Materials Science and Engineering 2020
author2 SU, PO-YI (Author)
author_facet SU, PO-YI (Author)
title Structural and Optical Properties of III-V Semiconductor Materials for Photovoltaics and Power Electronic Applications
title_short Structural and Optical Properties of III-V Semiconductor Materials for Photovoltaics and Power Electronic Applications
title_full Structural and Optical Properties of III-V Semiconductor Materials for Photovoltaics and Power Electronic Applications
title_fullStr Structural and Optical Properties of III-V Semiconductor Materials for Photovoltaics and Power Electronic Applications
title_full_unstemmed Structural and Optical Properties of III-V Semiconductor Materials for Photovoltaics and Power Electronic Applications
title_sort structural and optical properties of iii-v semiconductor materials for photovoltaics and power electronic applications
publishDate 2020
url http://hdl.handle.net/2286/R.I.62663
_version_ 1719368444577579008