Annealing Effect on the Structural and Optical Properties of Sol- Gel Deposited Nanocrystalline CdO Thin Films

Abstract

In this paper CdO thin films have been prepared by using SOL-GEL method with spin coating technique, by depoited four layers  of mixtuer solution contians Cadmium acetate dehydrate, Triethylamine, glycerol and ethanol.The spin coated solution were dried at 100°C and annealied at (300,350 and 400 ^oC temperatures ). The x-ray diffraction techniques and UV-VIS spectrophotometer have confirmed the structural and the optical properties the prepared thin films. CdO thin films were found to have polycrystalline nature with cubic rock salt phase. The crystallinity being improved, the FWHM decreases and the grain size of the CdO thin films increased with increasing the annealing temperatures. The average grain size is observed in the range  (23.97 - 30.47) nm which indicate that the prepared film have a nanocrystalline structure. From optical analysis, it can be seen that there are an increases in the absorbance and decreases in the trancemittance  of the prepared films with the increasing of the annealing temperatures.The optical band gap decreases  from 2.556, to 2.081 eV with increasing of annealing temperature fromm 300 to 400° C, this suggested that the optical band gap for CdO nanocrystalline thin films is strongly dependent on the annealing temperature.

Keywords: CdO thin films, Sol–gel spin–coating, Structural and Optical properties, annealing temperature.