Chemical bath deposition of cadmium sulphide on silicon nitride: Influence of surface treatment on film growth

Nanoparticulate cadmium sulphide was grown by a chemical bath method on PECVD silicon nitride with various surface treatments. It was found that the packing density of the film increased in the order: untreated surface < mercaptopropyl-derivatised surface < ultra-thin (discontinuous) gold- or platinum-treated surface. This behaviour was rationalised by assuming that surface concentrations of Cd²⁺ or S²⁻ could be increased over the bulk values by producing a surface with ‘soft base’ or ‘soft acid’ chemistry, respectively.Nanoparticle diameters were larger with ultra-thin platinum treatment than with gold. These observations may allow ordered arrays of cadmium sulphide nanoparticles to be prepared by a masking - gold seeding - bath deposition procedure.