Buried p-n junction formation in CuGaSe_2 thin-film solar cells

摘要

CuGaSe_2/CdS interfaces and the mechanism behind the hetero p-n junction formation were investigated using solar cell devices which demonstrated about a 10% energy conversion efficiency. It was found that the CuGaSe_2/CdS interface could be described as a CuGaSe_2/Cu-deficient Cu-Ga-Se layer (CDL)/CdS structure and the p-n junction was located at the CuGaSe_2/CDL interface that was present 50-100 nm from the CDL/CdS interface. While the difficulty of the realization of equilibrium n-type CuGaSe_2 has been generally recognized, this result suggests that CDL consisting of ordered vacancy compound phases such as CuGa_3Se_5 can play the role of an n-type material.