Study on optimum structure of AlInGaP top-cells for triple-junction space solar cells

Morioka, Chiharu*; Imaizumi, Mitsuru*; Sato, Shinichiro; Oshima, Takeshi; Kibe, Koichi*

Radiation resistance of (Al)InGaP solar cells was examined in this study. The epitaxial structure, such as aluminum contents or carrier concentration (CC) in the base layer, is varied, whereas the base layer thickness is maintained at 1 m. The cells are irradiated with 3 MeV protons up to the fluence of 110/cm. Remaining factors of short-circuit current and open-circuit voltage show no significant difference between AlInGaP and InGaP cells. The graded CC structure in the base layer is ineffective to improve radiation resistance in the case of (Al)InGaP cells with a thick base layer, which implies that radiation degradation is not primarily attributable to the decrease in minority-carrier diffusion length.