Influence of Cu Thickness and Annealing on the Properties of ZnS/Cu/ZnS Multilayer Films

Zinc sulfide (ZnS), copper (Cu) and ZnS thin films were deposited sequentially on high-borosilicate glass by radio-frequency magnetron sputtering at room temperature, and a ZnS/Cu/ZnS sandwich structure was obtained. Cu thin films with thickness ranging from 4 to 20 nm were used as an intermediate metal layer. The effects of Cu thickness and annealing treatment on the surface morphology and the electrical and optical properties of the ZnS/Cu/ZnS multilayer films were observed. The results show that the surface roughness of the multilayer films was reduced with increasing Cu thickness. The conductivity and transmittance of the multilayer-structure device were regulated by tailoring the Cu thickness, illustrating that the 16-nm-thick Cu film is beneficial for obtaining high conductivity and transmittance performance. The structural properties of the multilayer films annealed at different temperatures were also studied. The annealed multilayers exhibited a cubic zinc blende structure with a highly (111)-textured orientation. The film crystallinity was improved with increasing annealing temperature.