Crystallized InBiS₃ thin films with enhanced optoelectronic properties

In this paper, a one-step thermal evaporation approach was used for fabrication of indium bismuth sulphide thin films, and the synergetic effects of co-evaporation of two sources (indium granules and Bi₂S₃ powders) were investigated using different characterization techniques. X-ray diffraction (XRD) analysis confirmed the crystalline orthorhombic structure for the postannealed samples. Surface roughness and crystal size of the obtained film samples were increased with increasing annealing temperatures. Analysis using X-ray photoelectron spectroscopy showed the formation of the InBiS₃ structure for the obtained films, which is also confirmed by the XRD results. The optical absorption coefficient value of the annealed samples was found to be in the order of 10⁵cm-1 in the visible region of the solar spectrum. The optical band gap energy and electrical resistivity of the fabricated samples were observed to decrease (from 2.2 to 1.3 eV, and from 0.3 to 0.01 Ω-cm, respectively) with increasing annealing temperatures (from 200 to 350°C), indicating the suitability of the prepared InBiS₃ thin films for solar cell applications.