Structure, surface topography and optical characterization of Ag co – doped Cd1-xCuxO nanostructure thin films

Abstract

Cd_1-xCu_xO and Ag co-doped Cd_1-xCu_xO nanostructure thin films with x = 0.2 and different Ag content (0-8%) were deposited by chemical spray pyrolysis technique on glass substrates at a temperature of 350 ^oC. The XRD results showed that the prepared films have polycrystalline with low crystallinity nature for CdO cubic structure. The preferential orientation of all films was absorbed along (111) plane. CuO monoclinic phase has appeared with low intensity while the Ag cubic phase appeared only in 8% of Ag content. Structural parameters such as average crystallite size, dislocation density and micro-strain were also investigated. SEM images revealed that the surface morphology of the films consists of spherical shaped grains uniformly distributed without detectable micro-cracks and improved by Ag Co-doping. EDXS spectrum analysis confirmed purity and stoichiometry of the prepared compositions. AFM results showed that the surface topography and the surface quality of the deposited thin films can be controlled by the variation of the Ag co-doping concentration. Optical absorbance and transmittance of Ag co-doped Cd_1-xCu_xO thin films has high values in the visible and near infrared regions respectively and varied with Ag co-doping content. Direct optical energy band gap of Cd_1-xCu_xO exhibits a blue shift with Ag co-doping, due to the quantum size and Burstein–Moss (BM) effects. The increasing of optical energy gap was confirmed by the decrease in the Urbach tails energy E_U after Ag co-doping..