Spray pyrolysis synthesis of CuxFe1−xS2 and their structural, electronic and optical properties: Experimental and first-principles study

Iron pyrite, FeS2 (FS) and the chalcopyrite copper iron sulphide CuxFe1−xS2 (CFS) thin films were synthesized using chemical spray pyrolysis (CSP) deposition technique. The effect of different Cu concentration (1, 3, 5 and 7 at.%) on growth of these films was investigated. The as-synthesized CFS thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible (UV-Vis) spectroscopy. The XRD pattern of FS show a structured cubic phase with preferential orientation along (2 0 0) plane, and CFS crystallized in chalcopyrite (tetragonal) with preferential orientations along (1 1 2) plane with crystallite size 142-91 Å. Optical absorption data show that the band gap of spray deposited FS and CFS films is 0.920-0.558 eV and the absorption coefficients significantly modified with the increase of Cu concentration from 3.619 × 105 cm−1 to 4.231 × 105 cm−1. Furthermore, these results have been adopted in accordance with the first principles calculations of electronic structure.