Structural and optical properties of nanocrystalline tin sulphide thin films deposited by thermal evaporation

Thermal evaporation technique was used to fabricate the nanocrystalline tin sulphide (SbS) thin films of thicknesses 200 and 377 nm on good quality glass substrate. The various physical properties of deposited thin films have been investigated using X-ray diffraction (XRD), Atomic force microscopy (AFM), and ultraviolet-visible-near infrared spectroscopy at room temperature. X-ray diffraction analysis confirmed the orthorhombic phase of SnS films and the calculated lattice parameters have been calculated. The grain size, dislocation density and micro strain have been calculated using X-ray data. The result from AFM analysis shows that the surface of films was compact, dense and smooth. The optical band gap and types of transitions involved in the absorption process have been investigated. For allowed direct and indirect transition, the band gap values varied in the range 1.96-1.72 eV and 1.58-0.92 eV, respectively. The deduced values of the band gap suggest that the deposited thin films can be used in the fabrication of solar cell devices.