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Fabrication and characterization of grade doped InGaP/InGaAs/Ge triple-junction solar cells grown by MOVPE
- Author(s)
- Jung, sang hyun
- Alternative Author(s)
- Sang Hyun Jung
- Advisor
- 이재진
- Department
- 일반대학원 전자공학과
- Publisher
- The Graduate School, Ajou University
- Publication Year
- 2016-08
- Language
- eng
- Keyword
- Solar cells; graded doping concentration; III-V compound semiconductors; photovoltaics; multi-junction; tandem; power conversion efficiency; metalorganic vapor phase epitaxy; epitaxial growth
- Alternative Abstract
- III-V Compound semiconductor based multi-junction solar cells have been studied for the space photovoltaic and high efficiency concentrator solar cell applications. Recently, compound semiconductor based multi-junction solar cells have been reported on 46 % efficiency under high concentrated illuminations. The enhancement of photovoltaic conversion efficiency by optimizing the epitaxial structure of sub-cells is essential to further understand the multi-junction structures and realize higher efficiency. In this dissertation, I analyzed the graded doping effect of emitter and base layers on the performances of the InGaP/InGaAs/Ge triple-junction solar cells grown by metalorganic vapor phase epitaxy. I investigate the computer simulation and experimental results of photovoltaic conversion efficiency of the GaAs and InGaP single-junction and InGaP/InGaAs triple-junction solar cells as a function of the graded doping in the emitter and base using TCAD tool (APSYS 2010). The various solar cells are fabricated using a standard photolithography, metal deposition, rapid thermal annealing, wet-chemical etching processes, and chip isolations. Photovoltaic device parameters and conversion efficiency of the cells are measured under AM1.5 global light illuminations. First, the GaAs and InGaP single-junction and InGaP/InGaAs/Ge triple-junction solar cells have been simulated by varying the uniformly and graded doped emitter and base structures. In the GaAs single-junction solar cells with graded doped emitter and base layer, the sample with graded doped emitter and base layer has the higher photovoltaic conversion efficiency than that of other samples. In the InGaP single-junction solar cells with graded doped emitter and base layer, the sample with graded doped emitter and base layer has the higher photovoltaic conversion efficiency than that of other samples. In the InGaP/InGaAs/Ge triple-junction solar cells with graded doped top and middle cells emitter and base layers, the sample with graded doped emitter and base layer has the higher photovoltaic conversion efficiency than that of other samples. The graded doping concentration and Fermi level profiles of GaAs and InGaP single-junction and InGaP/GaAs/Ge triple-junction solar cells are studied. Second, the GaAs single-junction solar cells have been epitaxially grown on GaAs substrates using MOVPE by varying the graded doped emitter and base layer structures. I prepared four different GaAs single-junction solar cells having the uniformly doped emitter and base layer, the graded doped emitter and uniformly doped base layer, the uniformly doped emitter and graded doped base layer, and the graded doped emitter and base layer. Photovoltaic device parameters and external quantum efficiency of the GaAs single-junction cells are characterized under the one-sun and high concentration illuminations. For sample with graded doped base layer, higher photovoltaic conversion efficiency, short circuit current density and external quantum efficiency are measured as compared to other samples. The open circuit voltage of sample with graded doped emitter and base layer is higher than that of other samples. Third, the InGaP single-junction solar cells have been epitaxially grown on GaAs substrates using MOVPE by varying the graded doped emitter and base layer structures. I prepared four different InGaP single-junction solar cells having the uniformly doped emitter and base layer, the graded doped emitter and uniformly doped base layer, the uniformly doped emitter and graded doped base layer, and the graded doped emitter and base layer. Photovoltaic device parameters and external quantum efficiency of the InGaP single-junction cells are characterized under the one-sun and high concentration illuminations. For sample with graded doped emitter layer, higher photovoltaic conversion efficiency, short circuit current density and external quantum efficiency are measured as compared to other samples. The open circuit voltage of sample with graded doped emitter and base layer is higher than that of other samples. Finally, the InGaP/InGaAs/Ge triple-junction solar cells have been epitaxially grown on Ge substrates using MOVPE by varying the graded doped emitter and base layer structures. I prepared three different InGaP/InGaAs/Ge triple-junction solar cells having the uniformly doped top and middle cell emitter and base layer, the graded doped top cell emitter and middle cell base layer, and the graded doped top and middle cell emitter and base layer. Photovoltaic device parameters and external quantum efficiency of the InGaP/InGaAs/Ge triple-junction cells are characterized under the one-sun and high concentration illuminations. For sample with the graded doped top cell emitter and middle cell base layer, higher photovoltaic conversion efficiency, short circuit current density and external quantum efficiency are measured as compared to other samples. The open circuit voltage of sample with graded doped middle and top cell emitter and base layer is higher than that of other samples. The photovoltaic conversion efficiency of InGaP/InGaAs/Ge triple-junction solar cell is 40.46 % at 159.74 suns concentration illuminations.
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- Graduate School of Ajou University > Department of Electronic Engineering > 4. Theses(Ph.D)
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