The physics and modeling of gallium-arsenide solar cells
Abstract
Gallium arsenide is a versatile semiconductor used in many devices. Due to its nearly ideal bandgap energy for solar energy conversion and its compatibility with AlGaAs, gallium arsenide's use in solar cells has been widespread and is growing. Only its chief rival, silicon, is more popular as a high-efficiency material. To continue gallium arsenide's growth, this research was conducted for the purpose of finding improved models for single-crystal GaAs solar cells. The research objectives were: (1) to characterize experimental GaAs cells, (2) to develop predictive device models for AlGaAs/GaAs, and (3) to project the potential of GaAs-based cells. Considering the number of laboratories fabricating GaAs solar cells, there has been a surprisingly limited number of experimental studies that have sought the understanding of GaAs device physics. To extend our knowledge in this area, a study of laboratory-grown cells was conducted. Our goal was to uncover the mechanisms that limit the performance of today's best GaAs solar cells. The information derived from this study has been used to develop improved models that successfully predict GaAs solar-cell performance. A two-dimensional numerical simulation program, capable of modeling GaAs/AlGaAs heterostructures, was developed. The simulation program is the culmination of earlier research efforts on GaAs/AlGaAs device modeling. It is now possible, using the numerical simulation program, to accurately assess the potential of GaAs solar cells. The numerical model projects conversion efficiencies of over 30% under concentrated sunlight, supporting earlier forecasts that GaAs could play an integral part of future solar-cell technology.
Degree
Ph.D.
Advisors
Lundstrom, Purdue University.
Subject Area
Electrical engineering
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