Preparation and characterization of CuGaS2 thin films as a promising parent material for intermediate band solar cells

Copper gallium disulfide (CuGaS2, CGS) thin films were successfully prepared by sulfurizing Cu–Ga (CG) precursors in sulfur atmosphere which have been obtained through magnetron sputtering. Structural, chemical composition and optical properties of CGS films were analyzed by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy and UV–vis spectrophotometer. The results indicated that the CuGaS2 films with a single-phase structure had formed at 450 °C and the crystallinity of this phase was improved with the increase in temperature. The composition of the films contains mainly CuGaS2 chalcopyrite phase (I2 d). And the crystal lattice parameters were a=b=5.3544 Å and c=10.4707 Å at a sulfurization temperature of 600 °C. The UV–vis spectroscopy indicated that the values of band gaps varied in the range of 2.31–2.46 eV within the temperature increasing from 450 to 600 °C.