Variation of the key morphological,structural, optical and electrical properties of SILAR CdO with alkaline earth Ca2+ ions doping

Pristine and alkaline earth Ca²⁺ ions doped (Ca_xCd_1-xO (0 ≤ x ≤ 0.025)) CdO films were fabricated by SILAR technique on the soda lime glass substrates. The influence of increasing Ca content on the morphological, structural, optical and electrical properties of deposited films was analyzed. Metallurgical Microscope (MM), Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM) images of the samples exhibited that the morphology was dramatically changed with the addition of Ca to the synthesis solution when compared to the pristine CdO film. Energy Dispersive Spectrometry (EDS) analyses confirmed the presence of Ca in the doped films. X-ray diffraction (XRD) analysis of the pristine and Ca-doped CdO films exhibited cubic crystalline structure with preferred orientation of (111) and (200) direction. The existence of chemical bonding was confirmed by Fourier Transform Infrared Spectroscopy (FTIR) study. Optical studies revealed that the energy band gap were dependent on Ca-doping content in accordance with both Vegard's relation and Tauc's law calculations. The impedance analysis and four-point probe measurement results of CdO thin films were studied. Sheet resistances of the thin films were increased by Ca doping up to doping level of 1.5%. Further doping level causes degradation in sheet resistance.