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

Abstract

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 7at.%) 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 (200) plane, and CFS crystallized in chalcopyrite (tetragonal) with preferential orientations along (112) plane with crystallite size 142–91Å. Optical absorption data show that the band gap of spray deposited FS and CFS films is 0.920–0.558eV and the absorption coefficients significantly modified with the increase of Cu concentration from 3.619×105cm−1 to 4.231×105cm−1. Furthermore, these results have been adopted in accordance with the first principles calculations of electronic structure.