Preparation of Cu2ZnSnS4 thin films via electrochemical deposition and rapid thermal annealing

We fabricated metallic Cu–Zn–Sn (CZT) precursor thin films via electrochemical deposition from aqueous metal salt solution on Mo-coated soda-lime glass substrates, and the influence of the subsequent sulfurization condition on the morphology, composition and structure of the final Cu2ZnSnS4 (CZTS) thin films was investigated. A rapid thermal annealing equipment was used for a systematic control of the sulfurization process parameters. The as-deposited films are composed of binary metallic alloys, which can be converted to the highly crystalline CZTS phase after sulfurization at temperatures above 500 °C. The composition of the CZT film barely changes during the sulfurization, and a small amount of CuS-based secondary phases exists even at 550 °C. However, a quick post-annealing KCN treatment effectively and selectively removes the secondary phase, evidenced by the Raman spectroscopy and elemental.