Effect of Annealing Temperature on the Structural and Optical Properties of CdS Thin Films Deposited by CBD

CdS thin-films deposited by CBD offers ultrathin films along with the good structural, electrical and optical properties within a very low processing cost. CdS thin-films were deposited by CBD technique and the as deposited films were annealed at 200°C and 400°C temperature under vacuum environment. The as deposited and annealed films were characterized by X-ray diffraction and UV-Visible near infrared spectroscopy. A comparative study of crystallographic and optical properties between the as deposited and annealed films were investigated. Analysis on structural and optical properties showed that the annealed CdS thin films offer much better crystallinity and less lattice defects as compared to the as deposited films. Near about 90% transmittance is achieved for the as deposited films and the optical transmittance is quite reduced for the annealed films and at the same time, the transmittance has increased slightly in the blue region at 400°C annealing temperature. Moreover, thinner (near about 100 nm) CdS layer can be fabricated by CBD with high transmittance enhances the possibility of applying this layer as buffer layer for high performance thin-film solar cell fabrication.