Morphological evolution and structural properties of Cu2ZnSn(S,Se)4 thin films deposited from single ceramic target by a one-step sputtering process and selenization without H2Se

Cu2ZnSn(SSe)4 (CZTSSe) thin films were successfully deposited on TiN/Mo-coated glass substrate using RF-sputtering from single ceramic CZTSSe target, followed by annealing at 400-600 °C for 1 h in Se atmosphere. The influence of substrate heating (RT−300 °C) and post-selenization on the morphological, structural, and compositional properties of the films were investigated using X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy, as well as by Raman scattering and X-ray photoelectron spectroscopy. The crystallinity with preferential (1 1 2) orientation of the as-sputtered precursor films increased with increasing the substrate temperature and the selenization temperature. Compared with the thin films as deposited, post-selenization (400-600 °C) further improved the microstructure features and elemental compositions. The thin films selenized at 600 °C got dense microstructure and large grain size of 2 μm, nearly stoichiometric Cu-poor and Zn-rich compositions with Cu/(Zn + Sn + Sb) ∼0.78 and Zn/Sn ∼1.24, and tetragonal structure with lattice parameters a = 5.663 Å, c = 11.234 Å. This study provides an insight into the use of single ceramic CZTSSe target sputtering method to demonstrate the selenization conditions, such as substrate temperature and selenium partial pressure, for improving the film crystallinity, stoichiometry and grain growth.