Comments on Surface Studies and Surface Alteration of CuInSe2 Polycrystalline Thin Films

The effects of surface alteration on CuInSe 2 thin films by KCN etching and subsequent (NH 4 ) 2 S x sulfur passivation as well as the formation of higher bandgap CuIn(S,Se) 2 layer were investigated. After these chemical treatments, no oxygen uptake was observed and a significant number of sulfur atoms were found to diffuse into the Sb-incoporated CuInSe 2 thin films to form a stable and higher bandgap CuIn(S,Se) 2 layer. A model is proposed to explain how Sb atoms in CuInSe 2 thin films can create a pathway for fast replacement of Se by S atoms. Also, Cu segregation from Cu-rich CuInSe 2 thin films was directly verified for the first time by the experiments of angular dependence of x-ray fluorescence.