Growth kinetics and polymorphism of chemically deposited CdS films

Abstract

The kinetics of growth for chemical deposition of CdS films from alkalinesolutions of cadmium salts has been studied with respect to temperature ofdeposition and the relative concentrations of the various reactants in thesolution. It has been established that the growth of the film takes place eitherby ion-by-ion condensation of Cd⁺² and S^-2 ions or by adsorption of colloidalparticles of CdS formed in the solution, depending on the various depositionparameters and the method of preparation. The former process of growthresults in thin, hard, adherent and specularly reflecting films, whereas thelatter results in thick, powdery and diffusely reflecting films. Occurrence ofdifferent polymorphic phases of CdS (hexagonal and cubic) has been observed under different growth conditions. A model for growth mechanismhas also been proposed.