Annealing temperature dependent investigations on nano-cauliflower like structure of CdO thin film grown by sol–gel method

Abstract

This paper reports sol–gel derived CdO thin films on glass substrate with different annealing temperatures from 350 °C to 650 °C. The crystal structure and surface morphology have been investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. XRD pattern displayed rocksalt cubic structure of thin films and annealing temperature is optimized for good crystallinity of the thin film. SEM images of thin film revealed the cauliflower like nanostructure on the surface of thin film which is found sensitive to annealing temperature. Optical band gap decreases from 2.42 to 2.20eV with the increase in annealing temperature from 350 °C to 550 °C. The Urbach energy is also calculated for measuring the disorder in thin films for different annealed thin films along with Raman spectra of the thin film to check the crystal structural of CdO thin films. I-V measurements have performed for optimizing annealing temperature to achieve good conductivity, which is very useful for optoelectronics applications.