Investigate the growth mechanism of Cu2FeSnS4 thin films by sulfurization of metallic precursor

Cu2FeSnS4 (CFTS) thin films have been prepared on glass substrates by a process of sputtering metallic precursor with post-sulfurization. By means of various holding times, the growth mechanism of CFTS has been determined by X-ray diffraction and Raman patterns. Three steps have been involved, the binary-phases CuSx, FeSx and SnSx are synthesized in the preliminary stage, and afterwards, CuSx reacts with FeSx to generate ternary-compound CuFeS2. At last, the target product CFTS is obtained with the increasing holding time of sulfurization. All the thin films have smooth and closely packed surface, and longer holding time is in favor of the grain growth. The thickness of these thin films is around 1 µm.