Preparation and characterization of copper zinc tin sulfide-selenide thin films using a single target RF sputtering method

Abstract

Copper zinc tin sulfide-selenide (CZTSSe) thin films have been prepared from a single alloyed CZTSSe target using one-step RF plasma magnetron sputtering technique. The films morphology, stoichiometry and crystalline properties have been examined as a function of the target to substrate distance, the deposition power and the substrate type. It was found that; within the range of the investigated target to substrate distance; better film crystallization was achieved when this distance equals to the target diameter, namely 5 cm in this work. An appropriate film thickness of 1.1 μm along with a more adequate compositional ratio equals to 14% Cu, 14% Zn, 16% Sn and 56% (S+Se) were obtained at low deposition power of 30 W with gradually decreasing the power during the deposition process. In this case, the low deposition rate resulted in proper compositional ratio, but the film crystallinity was found to be affected by the substrate type. As such, it was found that the use of a crystalline silicon substrate instead of the amorphous Soda Lime Glass substrate enhanced the film crystallinity.