Effect of Sulfurization Time on Properties of CZTS Thin Films by Solid-state Sulfurization

Cu₂ZnSnS₄ (CZTS) thin films were prepared by solid-state sulfurizing Cu-Zn-Sn(CZT) metallic precursors. The effect of sulfurization time on phases, chemical composition, surface morphology and optical properties was investigated by X-ray diffraction (XRD), Raman spectrum, energy dispersive of X-ray (EDS), scanning electron microscope (SEM) and UV-Vis, respectively. The results show that with the sulfurization time and content of Cu increase, Zn particularly decreases. The films that sulfurized over 40min occur with impurities like SnS, Sn₂S₃ and Cu₂SnS₃, which lead smaller optical band gap. When the sulfurization time is 20min, the sample is single phase CZTS thin film, which surface is uniform and even, Cu-poor and Sn-rich. The absorption coefficient is over 10⁴cm^-1. The band gap energy is estimated 1.56eV