Optical properties of highly stable silver thin films using different surface metal layers

Abstract

Previously, we developed a highly stable silver thin film where surface and interface Al nanolayers were used to suppress agglomeration by annealing. In this study, we focus on reflectance of the silver film. The Al and Ti surface layers were deposited on silver films by RF magnetron sputtering. The surface morphology and reflectance of Ag, Al/Ag and Ti/Ag films were measured using an atomic force microscope and a spectrophotometer, respectively. It is found that the surface roughness of all the films is very small and it decreased by deposition of Al and Ti layers. We found 1-nm-thick Al or Ti layer deposited Ag films showed the same reflectance as silver single film. But a decrease of the reflectance was observed when the thickness of the Al or Ti layer was increased to 3 nm. Consequently, it is found that the optimum thickness of Al or Ti layer deposition is 1 nm in highly stable silver thin films. Their optical properties were influenced by both metal and metal oxide of the surface layer.