Growth Kinetics and Polymorphism of Chemically Deposited CdS Films

The kinetics of growth for chemical deposition of CdS films from alkaline solutions of cadmium salts has been studied with respect to temperature of deposition and the relative concentrations of the various reactants in the solution. It has been established that the growth of the film takes place either by ion‐by‐ion condensation of Cd +2 and S −2 ions or by adsorption of colloidal particles of CdS formed in the solution, depending on the various deposition parameters and the method of preparation. The former process of growth results in thin, hard, adherent and specularly reflecting films, whereas the latter results in thick, powdery and diffusely reflecting films. Occurrence of different polymorphic phases of CdS (hexagonal and cubic) has been observed under different growth conditions. A model for growth mechanism has also been proposed.