Tailoring of structural, opto-nonlinear and electrical properties of CdO thin films via Zn and Ag co-doping for optoelectronics applications

Abstract

Sol-gel spin coating technique was used to develop Zn and Ag co-doped CdO thin films with 3.0 wt% Zn and various Ag doping concentrations. A cubic structure and a preferred orientation along (111) growth plane of samples was confirmed from films diffractograms analysis. The crystallites sizes of the samples were calculated and found about ∼33–44 nm. A further investigation of the structural phase of the films was carried out using Raman spectroscopy. The elemental composition of the films was examined using EDX technique which confirmed the presence of all elements. The collected EDX mapping spectra revealed a successful Zn and Ag co-doping of CdO films with a uniform elemental distribution. A controlled tailoring of the optical band gap of the film was achieved via Zn and Ag co-doping of CdO films. The band gaps of films were obtained from the Uv–vis absorbance spectra and were found to be in the order ∼1.87–2.32 eV. A significant improvement in nonlinear optical parameters was observed for the Zn doped CdO matrix with high Ag doping concentrations where χ(3) was estimated to be about 5.52 × 10−12-4.16 × 10−12 esu and (n2) ∼1.84 × 10−11-1.51 × 10−10 esu; respectively. On the other hand, Hall measurements of the grown films revealed interesting improvements in the carrier concentrations and conductivity. Films I–V characteristics show an ohmic contact with enhanced conducting behavior which suggests that the developed co-doped CdO films are promising for optoelectronics applications.