Effects of Cu doping on the structural, photoluminescence and impedance spectroscopy of CoS₂ thin films

Copper-doped cobalt sulfide (Cu_xCo_1−xS₂: x = 0–0.1) nanocrystalline thin films were deposited on glass substrates using successive ionic layer adsorption and reaction (SILAR) technique. The influence Cu element concentration on nanostructural, morphological, photoluminescence and impedance properties of Cu_xCo_1−xS₂ thin films were examined by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), electron dispersive X-ray (EDX) photoluminescence (PL) and impedance spectroscopy. XRD results revealed that all prepared films consist of pure cubic phase of CoS₂ pyrites structure and were well crystallized with the preferentially oriented along (200) plane. Cu doping resulted in a significant increase in the crystallinity of the films and a noticeably alteration in crystallite size. FESEM images revealed that the deposited thin film having spherical grain distribution and the grain sizes decreased from 56 to 34 nm with increasing Cu doping level. The EDX analysis confirmed the stoichiometry of prepared thin films. Photoluminescence (PL) spectra display the broad emission bands centered at 411 with a hump at 417 nm, due to the intrinsic defects. From the impedance spectroscopy analysis, we examined the equivalent circuit and frequency-dependent relaxation phenomenon in dielectric dipoles, loss of electrical energy and AC conductivity of the pure and Cu-doped thin films. Finally, all properties have been discussed, as an impartial of the research work, in terms of the Cu doping content.