Effects of supersaturation on CdS film growth from dilute solutions on glass substrate in chemical bath deposition process

CdS films were prepared on a glass substrate and their growth was analyzed as a function of the supersaturation ratio in dilute solutions. Nanocrystalline CdS with a hexagonal (wurtzite) structure is present in the CdS films and aggregated into colloidal particles. The particle size increases from 117 nm to 357 nm when the relative supersaturation ratio (S_r) increases from 0.4 to 1.0, but particle size decreases to 149 nm and the absorption edge blue shifts from 488 nm to 456 nm when S_r increases further to 4.0. The evolution of the CdS film is explained on the basis of the proposed growth kinetic model.