The influence of CdS quantum dots incorporation on the properties of CdO thin films

The aim of our work is to obtain nano-structured cadmium oxide (CdO) thin films by sol-gel spin coating method and to investigate the effects of cadmium sulfide quantum dots (CdS QDs) doping on the structural modification and surface morphology evolution. The characterizations of the structural and morphological properties of the Cds QDs doped CdO thin films have been carried out by means of X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), respectively. XRD results show that all the thin films have cubic poly-crystal structure and the intensities of the peaks of the crystalline phase increase with the increase in CdS QDs concentrations. From SEM images, the distinct variations in the morphology of the thin films were also observed. In addition, the evolution of surface morphology, roughness and granularity has been characterized by Atomic Force Microscopy (AFM). We also discuss the influence of doping on the optical characteristics of nano-structured CdO thin films based on optical characterization. Thus, we have performed the optical characteristics of the device such as transparency, band gap energy, Urbach tail, refractive index, high frequency dielectric constant, etc. Refractive index and optical high dielectric constant of the thin films decreased while transparency increased with the increase in CdS QDs concentrations. The optical band gap of the thin films increases from 2.23 to 2.51 eV with the increase in CdS QDs concentrations due to the Moss–Burstein effect