Variation of the structural, optical and electrical properties of CBD CdO with processing temperature

Nanostructures of CdO thin films are prepared by chemical bath deposition (CBD) technique. The synthesized film is annealed in static air by using the hotplate at 373, 473, 573 and 673 K for 10 min. The effect of annealing temperature on structural, morphological, optical and electrical properties of CdO thin films has been investigated. The prepared thin films are characterised by X-ray diffraction (XRD), atomic force microscope (AFM), optical reflection microscope (ORM), UV-Visible Spectrophotometer and electrical resistivity. XRD shows the emergence of the cubic phase of CdO film in a preferred orientation (111) plane at 573 K. The AFM and ORM show that CdO films have smooth homogeneous surface in the formula with the emergence of nanoclusters gathering as nanoparticles with the average of grain size about 100 nm at 573 K. The optical properties prove that deposited films have high transparency within the visible range of the spectrum that reaches to more than 85% with a wide band gap that extends from 2.42 eV to 2.7 eV. The electrical properties of the CdO films show that resistivity decreases with increased annealing temperatures. In addition, it is proved that more than one activation energy appears and they change according to the temperature of annealing and this comes as a result of the polycrystalline structure. This study indicates that the properties of CdO thin films could be improved with annealing temperature and these films can be used in many technological applications.