Effect of the cadmium ion source on the structural and optical properties of chemical bath deposited CdS thin films

The chemical bath deposition (CBD) technique has been successfully used to deposit cadmium sulphide from cadmium chloride and cadmium acetate as the c admium ion source and thiourea as the sulphur source on both glass microsco pe slide and indium tin oxide coated grass substrates. Various properties o f the films such as surface morphology, crystallinity, optical properties a nd resistivity have been investigated. XRD patterns reveal that the CdS fil ms deposited from cadmium chloride have an hexagonal structure. Their prefe rential orientation changes from (002) to (100) with the thermal annealing. Films deposited from cadmium acetate are amorphous but improve their cryst allinity with annealing. SEM analysis shows that the grains of the as depos ited films are randomly shaped and appear to be bigger in the case of the C dS prepared from cadmium chloride. The optical transmission of the layers a re in the 70-80% range for wavelength above the band gap absorption which m akes them more appropriate as window material in heterojunction solar cells .