Fabrication of a GaInN/GaInP/GaInAs/Ge four-junction solar cell using the wafer bonding technology

We fabricated a GaInN/GaInP/GaInAs/Ge four-junction solar cell by wafer bonding a GaInN solar cell and a GaInP/GaInAs/Ge three-junction solar cell. We performed our wafer bonding at high pressure (500 N) and temperature (450 °C) by using p-type GaN and n-type GaAs. The open-circuit voltage (VOC), JS...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 2019-07, Vol.58 (7), p.72003
Main Authors: Takahashi, Kazuya, Shinoda, Ryoji, Mitsufuji, Syun, Iwaya, Motoaki, Kamiyama, Satoshi, Takeuchi, Tetsuya, Hattori, Tomokazu, Akasaki, Isamu, Amano, Hiroshi
Format: Article
Language:English
Subjects:
Bonding
Gallium indium phosphide
Indium gallium arsenides
Open circuit voltage
Photovoltaic cells
Solar cells
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Summary:We fabricated a GaInN/GaInP/GaInAs/Ge four-junction solar cell by wafer bonding a GaInN solar cell and a GaInP/GaInAs/Ge three-junction solar cell. We performed our wafer bonding at high pressure (500 N) and temperature (450 °C) by using p-type GaN and n-type GaAs. The open-circuit voltage (VOC), JSC, and fill factor of our four-junction solar cell under the condition of AM 1.5 G, i.e., 1 sun are 2.85 V, 0.219 mA cm−2, and 0.74, respectively. The improved VOC of our four-junction solar cells was confirmed by a series connection. The JSC is almost comparable to the theoretical value (itself based on the assumption of an ideal series junction), but the VOC is approximately 1 V less than that predicted by theory. Our research will improve the solar cell efficiency and help meet future energy needs.
ISSN:0021-4922
1347-4065
DOI:10.7567/1347-4065/ab26ad