Structural and optical properties of Cu2SnS3 thin films obtained by SILAR method

Cu2SnS3 thin films were obtained by annealing of SILAR deposited films at 350°C for 1 hour in sulphur atmosphere. The structural and optical properties of the films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and optical absorption measurements, before and after annealing. The XRD results showed that the annealing process transformed the crystal structure of the films from amorphous to polycrystalline. SEM images revealed that the surface morphology of films was changed after annealing while EDAX analysis showed that the films were excess in copper concentration before and after annealing. Optical absorption measurements confirmed that the direct band gap of films decreased from 1.27 eV to 1.21 eV with annealing.