Colloidal synthesis of nanostructured pure ZnO and Cd doped ZnO thin films and their characterization

Thin films of intrinsic and Cd-doped ZnO with different cadmium concentrations were prepared by colloidal route technique associated with dip-coating onto glass substrates. Zinc acetate dehydrate, Cadmium acetate, methanol and ethanolamine were used as a starting materials, solvent and stabilizer, respectively. Nanostructured ZnO thin films with different concentrations of Cd doping (0, 2 and 10 wt%) are annealed at 500 °C for 2 h. The films were characterized by different methods to understand their structural, optical and electrical properties such as the film surface is with a ganglia-like structure as observed by Environmental Scanning Electron Microscopy (ESEM). The films were characterized by grazing incidence X-ray diffraction, its comprise of ZnO nanocrystallites with hexagonal crystal structure with a presence of CdO nanocrystallites with cubic crystal structure in 10% Cd-doped ZnO film (ZnO/CdO nanocomposite), as revealed by means of X-ray diffraction (XRD), the Raman and the Rutherford backscattering spectrometry (RBS) confirmed that. All films exhibit a transmittance above 75–90% along the visible range up to 800 nm and a sharp absorption onset about 375 nm corresponding to the fundamental absorption edge 3.2 eV (UV–vis). Photoluminescence of the films showed an ultraviolet UV and visible emissions like violet, blue and green related to defects.