An investigation of annealing and (Zn + Co) co-loading impact on certain physical features of nano-structured (CdO) thin films coated by a sol-gel spin coating process

Abstract

Transparent conducting pure and (Co + Zn) co-loaded CdO films were coated by sol-gel spin coating technique with various (cobalt + Zinc) co-loading concentrations. XRD analysis explained the polycrystalline nature of the coated samples with cubic crystal structure along (111) plane being the preferential orientation. The surface morphology and thickness of the prepared thin-films were analyzed by Field Effect Scanning Electron Microscopy (FESEM) and cross-sectional FESEM, respectively. The RMS surface roughness was analyzed by Atomic Force Microscopy AFM measurements. The existence of Cd, Co, Zn, and O elements was confirmed by “Energy-dispersive X-ray Spectroscopy (EDS) spectra”. The red-shift of energy-gap from 2.76 eV to 2.20 eV was carried out by using the Tauc;s and Davis-Mott mathematical relations, in high absorption regions. The shifting from the n-type to p-type semiconductor behavior for the coated samples was estimated by 4 points probe and average Hall coefficient value sign.