Synthesis of Cu₂ZnGeS₄ thin film via sulfurization of RF magnetron sputtered precursor

Quaternary Cu₂ZnGeS₄ thin film was synthesized by sulfurization of radio-frequency magnetron sputtered precursor at a high temperature for the first time. The precursor was deposited sequentially on a glass substrate by the sputtering method from high purity Cu, Zn and Ge elemental targets with the stacking order: Ge/Zn/Cu/glass. Energy dispersive X-ray mapping results demonstrate that the Cu, Zn, Ge and S elements are uniformly distributed in Cu₂ZnGeS₄ thin film. The surface micrograph shows a compact and densely packed morphology. The X-ray diffraction results and Raman spectroscopy analysis indicate that the as-prepared thin film has pure phase. It can be confirmed that the microstrain and crystal disorder exist in the thin film by Williamson–Hall analysis method. The absorption spectrum demonstrates that the value of the band gap for Cu₂ZnGeS₄ thin film is 1.85 eV. These results indicate that sulfurization of magnetron sputtered precursor is a suitable process for the growth of Cu₂ZnGeS₄ thin film.