ABSTRACT
The oxidation of Cu-poor Cu(In,Ga)Se2 thin films in air is investigated using x-ray photoelectron spectroscopy and secondary ion mass spectrometry. The thermal oxidation in air at 200 °C leads to the formation of In2O3, Ga2O3 and SeO2 at the surface. The oxidation at room temperature is strongly influenced by the air humidity and leads additionally to the formation of free selenium. Furthermore, the results show that the short-term thermal oxidation affects mainly the surface and the long-term room temperature oxidation affects the bulk as well. The oxidation of the absorber layer in humid air has a negative effect on the performance of Cu(In,Ga)Se2/CdS/ZnO solar cells.
