Evaluation of the junction interface of the crystalline germanium heterojunction solar cells

A junction interface of hydrogenated amorphous silicon/crystalline germanium heterojunction solar cells that employ substrates of different crystalline orientations and PH3 exposure interface treatment was evaluated. We confirmed that the degree of heteroepitaxial growth depends on the crystalline orientation and is suppressed by PH3 exposure treatment. In addition, the PH3 exposure treatment forms a depletion layer near the interface in the crystalline germanium substrate. The heteroepitaxial growth and depletion layers have a great effect on the solar cell performance. Accordingly, a conversion efficiency of 6.54% was obtained by optimizing the interface properties.