UNDERLAYER ROUGHNESS INFLUENCE ON THE PROPERTIES OF Ag THIN FILM

The effects of the roughness of ZnS underlayer on the microstructure, optical, and electrical properties of nanometer Ag thin film have been investigated in this paper. Nanometer Ag thin films in glass/ZnS/7.5 nm Ag/30 nm ZnS stacks have been deposited and analyzed. In the stacks, the underlayers of ZnS have been sputtered with various thicknesses to generate various surface roughnesses. The X-ray diffraction (XRD) has been used to study the crystal structure of Ag films. The surface topography and the roughness of ZnS underlayer have been analyzed by atomic force microscopy. The sheet resistant will become larger as the increasing of the roughness. The optical constants can be derived by fitting the transmission and reflectance spectrum. From optical constants comparison of Ag films, with the surface of the stack becoming rougher, it was found that the refractive index will increase but the extinction coefficient will decrease.