Influence of substrate temperature on CuxSnSx+1 thin films prepared by Co-sputtering and H2S annealing

CuxSnSx+1 (CTS) thin films were deposited by co-sputtering of Cu and Sn targets and annealing the films in an Ar:H2S atmosphere. The substrate temperatures were fixed at room temperature, 100, 175, and 250 degrees C during film deposition. The deposited films were then annealed in an Ar:H2S atmosphere at 550 degrees C for 1 h. The Cu/Sn ratio decreased sharply with substrate temperature. In the annealed samples, the Cu/Sn ratio increased for films deposited at room temperature, 100, and 175 degrees C, and decreased for films deposited at 250 degrees C, showing the temperature dependence of CuxSn alloy formation. Additionally, Cu3SnS4 phase formation was observed in the films grown at room temperature, whereas the films showed a Cu2SnS3 phase at higher substrate temperatures.