Developing an understanding of the processes controlling the chemical bath deposition of ZnS and CdS

The deposition of cadmium sulfide by chemical bath methods is straightforward and involves an alkaline solution of a cadmium salt, a complexant and a chalcogen source, often thiourea or thioacetamide. Supersaturation of the bath with respect to ‘Cd(OH) 2 ’ is necessary for the deposition of good quality films under a wide range of conditions. In contrast zinc sulfide is more difficult to deposit. In this paper we discuss the literature concerning the deposition of these chalcogenides and use equilibrium models to rationalise many of the observations found in the literature. Strategies for the deposition of high quality films of ZnS by CBD are discussed.