Preparation and Characterization of Cu₂ZnSn(S,Se)₄ Thin Films by Sulfurization of Cu-Zn-Sn-Se Precursor Layers

We fabricated Cu2ZnSn(S,Se)₄ (CZTSSe) thin films by sulfurization of co-evaporated Cu-Zn-Sn-Se precursor layers under a mixed atmosphere of Ar and H₂S. The concentration of H₂S in the sulfurization chamber was adjusted to control the replacement of Se by S in CZTSSe thin films. The effect of applying different sulfurization atmospheres was analyzed using X-ray diffraction (XRD), Raman scattering, and secondary electron imaging. XRD patterns and Raman spectra confirmed the formation of polycrystalline CZTSSe thin films. The anion compositions of CZTSSe samples, which depended on the concentration of H₂S, were estimated by using the peak heights of A modes in Raman spectra. To further analyze Raman scattering of CZTSSe thin film, we used a diamond anvil cell to apply a high pressure environment of up to 5.13 GPa on the CZTSSe sample. The effect of H₂S concentration on the crystallinity of the CZTSSe thin films is also discussed.