Growth of ultrathin chemically-deposited CdS films from an ammonia-thiourea reaction system

Polycrystalline CdS films, with thicknesses typically 0.005 to 0.5 μm, have been chemically deposited from an ammonia-thiourea system. The influence of reaction parameters (i.e. concentration of reactants and pH) on film growth rate were determined and modelled. The results of a kinetic study are presented, resulting in the formulation of a growth rate formula. The deposited film properties are dependent on temperature, stirring, relative concentrations of the solution reactants, type of reactants, and solution pH. Thin film growth is thermally activated with an activation energy E_A∼5×10²³ eV/mol.