XPS analysis and structural characterization of CZTS thin films prepared using solution and vacuum based deposition techniques

This work describes a procedures to grow single phase Cu₂ZnSnS₄ (CZTS) thin films with tetragonal-kesterite type structure, using solution and vacuum based deposition techniques. The solution based deposition approach involves sequential deposition of Cu₂SnS₃ (CTS) and ZnS films, where the CTS compound is synthesized in one step process by simultaneous precipitation of Cu2S and SnS₂ performed by diffusion membranes assisted CBD technique and the vacuum based approach includes sequential evaporation of the elemental metallic precursors under a flux of sulphur supplied from an effusion cell. X-ray diffraction analysis (XRD) which is mostly used for the phase identification can not clearly distinguish the formation of secondary phases such as Cu₂SnS₃, since both compounds have the same diffraction pattern; therefore the use of a complementary technique is needed. Raman scattering analysis was used to distinguish these phases. Further, the chemical elemental composition and oxidation states of both type of CZTS films were studied by X-ray photoelectron spectroscopy (XPS) analysis.