Effects of selenization parameters on growth characteristics of the Cu(In,Ga)Se2 films deposited by sputtering with a Cu-In-Ga, Cu-In-Ga2Se3, or Cu-Ga-In2Se3 target and a subsequent selenization procedure at 550–700 °C

Cu(In,Ga)Se2 (CIGSe) thin films were prepared by sputtering with a Cu-In-Ga, Cu-In-Ga2Se3, or Cu-Ga-Se2Se3 target and a subsequent selenization procedure at 550–700 °C. The utilization of In2Se3 is to avoid the pre-matured formation of CuInSe2, which form easily during selenization when metallic In exists in an as-deposited film. CIGSe films prepared with a Cu-Ga-In2Se3 target had shown the composition uniformity. The variations of microstructure, structure, and electrical properties with selenization temperature for films deposited by a Cu-Ga-In2Se3 target were investigated under a one-step or two-step selenization procedure. Selenization mechanism was proposed and its problems were presented. The influence of crystallinity and thin film microstructure on performance of electrical properties were investigated. CIGSe films sputtered by a Cu-Ga-In2Se3 target after two-step selenization at 600 °C showed a good microstructure and high mobility of 106 cm2 V−1 s−1, avoided a two-layer structure formation in the CIGSe film, and obtain a better crystallinity because of high solute solubility in the selenium solution during a selenization procedure.