Deposition of single-phase monoclinic Cu₂SnS₃ thin films on Mo-coated substrates by dual-source fine-channel mist CVD

Abstract Single-phase monoclinic Cu 2 SnS 3 (CTS) thin films on Mo-coated soda-lime glass (SLG) substrates were fabricated through dual-source fine-channel mist chemical vapor deposition (CVD) by optimizing the deposition sequence and annealing process. The conventional deposition process using mist CVD caused Mo dissolution, thereby hindering CTS deposition on the Mo-coated SLG substrate. Therefore, to prevent Mo dissolution, a two-step deposition process was employed—initially, a Cu–Sn–S thin film was deposited briefly, followed by drying before the second deposition. This approach enabled deposition of CTS thin films on the Mo-coated SLG substrates. In addition to the fabrication of single-phase monoclinic CTS thin films, we attempted in situ annealing, annealing with flowing mist, and cover annealing, i.e. annealing while covering the deposited film with an SLG substrate in in an N 2 atmosphere. After in situ and cover annealing processes, the Raman spectra showed only single-phase monoclinic CTS.