Annealing temperatures effects on structural and optical properties of CdO thin films

In this study, the structural and optical properties of CdO thin films subjected to heat treatment at different temperatures were investigated. CdO films were deposited on glass substrates by thermal evaporation. X-ray diffraction technique (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and atomic force microscopy (AFM) measurements were taken to investigate the crystal structure and surface morphology of the prepared films UV-vis spectrometer was utilized to measure the optical properties. As a result of XRD measurements, it was observed that the CdO thin film without and with heat treatment has a cubic crystal structure. The increase in the sharpness of x-ray peaks in CdO thin films with heat treatment means an increase in crystallization, and the calculated crystal sizes showed that the crystal size generally tends to increase with a rise in the applied annealing temperature. As can be seen from the SEM images, it was observed that the small grains on the surface were replaced by large grains as a result of the merger of small grains with each other with rising annealing temperature. The optical band gap Eg, which changes with heat treatment, was calculated to be between 2.45 and 2.27 eV. It was concluded that heat treatment improves the conductivity of CdO thin films by reducing the Eg value.