Development of InGaP/GaAs/InxGa1-xAs//InyGa1-yAs Four-junction Solar Cells by Surface Activated Bonding

Takashi Shimasaki1, Kentaroh Watanabe2, Hassanet Sodabanlu2, Yoshiaki Nakano1, Masakazu Sugiyama1,2 1Department of Electrical Engineering, The University of Tokyo, Tokyo, --, Japan /2Research Center for Advanced Science and Technology, The University of Tokyofor , Tokoyo, --, Japan

4-junction solar cells were fabricated by surface activated bonding (SAB) of inverted metamorphic triple-junction solar cells(IMM3J) and In0.53Ga0.47As single junction solar cells. 4-junction solar cells clearly improved Voc compared to IMM3J, ensuring the function as 4-junction solar cells. However, current mismatches between IMM3J and In0.53Ga0.47As, resulting in the decrease of maximum power. Thin type of IMM3J was also tried to relieve the current mismatch, and 4-junciton solar cell composed of thin IMM3J and front hetero junction In0.53Ga0.47As was the closest to the current match condition under AM0 illumination, showing the possibility of application for space.