| Project/Area Number |
06402064
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
エネルギー学一般・原子力学
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| Research Institution | Nagoya Institute of Technology |
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Principal Investigator |
UMENO Masayoshi Faculty of Engineering, Nagoya Institute of Technology Prof., 工学部, 教授 (90023077)
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| Co-Investigator(Kenkyū-buntansha) |
SHAO Chunlin Faculty of Engineering, Nagoya Institute of Technology A.Prof., 工学部, 助教授 (20242828)
EGAWA Takashi Research Center for Micro-Structure Devices, Nagoya Institute of Technology A.Pr, 極微構造デバイス研究センター, 助教授 (00232934)
SOGA Tetsuo Instrument & Analysis Center, Nagoya Institute of Technology A.Prof., 計測分析センター, 助教授 (20197007)
JIMBO Takashi Research Center for Micro-Structure Devices, Nagoya Institute of Technology Prof, 極微構造デバイス研究センター, 教授 (80093087)
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| Project Period (FY) |
1994 – 1996
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| Keywords | tandem solar cell / GaAs / AlGaAs / Si substrate / thermal cycle annealing / dislocation / stress / minority carrier lifetime |
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| Research Abstract |
Compound semiconductor/Si tandem solar cell has attracted attention for high efficiency solar cell more than 30%. The important technology to obtain a high efficiency solar cell is to reduce the dislocation and the stress of GaAs on Si. We reduced the dislocation density and the stress by thermal cycle annealing (TCA) and YAG laser irradiation, respectively. The growth was performed by rf-heated metalorganic chemical vapor deposition. The dislocation density is reduced with increasing the TCA temperature during the growth. The minority carrier is improved to 3.36 ns with utilzing the 1000ﾟC TCA.The buffer layr of InGaAs/GaAs strained layr superlattice is also effective to improve the minority carrier lifetime. The bending of the dislocation was confirmed at the interfaces by the transmission electron microscopy. The dislocation density of GaAs on Si with 1000ﾟC TCA is 9*10^6 cm^<-2>. The stress-free GaAs was obtained on Si substrate with optimizing the YAG laser pulse irradiation conditions such as laser power, pulse width, number of irradiation, etc.
AlGaAs/Si and GaAs/Si tandem solar cell were fabricated using the high quality cystal. The conversion efficiency was improved with utilizing the compositionally step graded emitter layr. The current matching was realized by the Al_<0.15>Ga_<0.85>As/Si tandem solar cell, and the efficiency was 21.2 % under two-terminal configuration. In the case of GaAs/Si tandem solar cell, 22.1% was obtained (top cell : 17.7%, bottom cell : 4.4%) under three-terminal configuration. This is the highest efficiency for monolithic for compound semiconductor/Si tandem solar cell as ever reported.
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