Simulation study of effect of heteroepitaxial growth on crystalline germanium heterojunction solar cell

摘要

The impact of crystalline silicon (c-Si) heteroepitaxial growth on a crystalline germanium (c-Ge) heterojunction solar cell has been investigated by numerical simulation. It is revealed that the defect state density of the c-Si heteroepitaxial growth layer does not significantly affect the conversion efficiency, in contrast to the case of a c-Si heterojunction solar cell. A valence band offset between the c-Ge and the c-Si heteroepitaxial growth layer prevents recombination at the defect states. On the other hand, interface defect states have a greater impact on the performance due to the weak built-in potential. From these results, reducing the effect of the interface defects is essential to improve the solar cell performance. Possible ways to reduce the effect of the interface defect states are also discussed. (C) 2015 The Japan Society of Applied Physics