Influence of different S/Se ratio on the properties of Cu₂Sn(S_xSe_1-x)₃ thin films fabricated by annealing stacked metal precursors

Cu₂Sn(S_xSe_1-x)₃ (CTSSe) thin films were successfully synthesized by annealing process from stacked precursors prepared on soda lime glass substrates by radio frequency magnetron sputtering technique. The structural, morphological, optical and electrical properties in wide composition range (0 ≤ x ≤ 1) have been investigated. Energy dispersive X-ray measurement indicates that the ratio of sulfur and selenium in thin films could be tuned. X-ray diffraction patterns demonstrate that the lattice constant decreases linearly with the increase in sulfur content. Raman spectra analysis confirms that the dominant peaks present linear variation with x value. Optical characterization reveals that the band gap energy can be tuned monotonously from 0.60 to 0.92 eV. Further electrical measurement results show that all samples are p-type semiconductor and the mobility of CTSSe decreases when S replaces gradually Se.