Structural, Morphological and Optical Properties of Cadmium Sulphide Thin Films Grown Using Chemical Bath Deposition Technique

Cadmium sulphide (CdS) thin films were deposited onto glass substrates by the chemical bath deposition (CBD) technique. Aqueous baths of cadmium sulphate and thiourea were used as sources of cadmium (Cd+2) and sulphur (S-2) ions, respectively. The influence of the varied bath temperature from 65 degrees C to 85 degrees C in a step of 10 degrees C on the crystallographic structure, morphology as well as optical properties of as-deposited films were investigated in detail. Increasing bath temperature can promote phase transformation from cubic to hexagonal and improvement of crystallinity in CdS films. CdS film deposited at 85 degrees C shows compact and smooth surface, and excellent transmission in visible light range. The band gaps are found to decrease from 2.52 eV to 2.36 eV with the increase of bath temperature.