IntroductionRecent years, chalcopyrite semiconductors have been successfully applied as absorber layers for polycrystalline thin-film solar cells. Among the ternary compound semiconductors, CuInS2 thin films with a direct bandgap of about 1.50 eV and a large absorption coefficient in the range of 104-105cm-1[1] are one kind of the most promising optical absorbers for high efficiency thin film solar cells.To date, CuInS2-based solar cells have shown conversion efficiency of about 12. 5%[2]. They exhibit long-term stability without any signs of degradation.