Optical properties of Au/SiO2 nano-composite films prepared by induction-coil-coupled plasma sputtering

Au/SiO2 nano-composite thin films with 3 to 65 vol% An were prepared by induction-coil-coupled plasma sputtering, and the effect of heat-treatment on the nano-structure and optical property of the films were investigated. The mean diameter of the An particles in the as-deposited films was about 8 nm and increased from 10 to 30 nm after the heat treatments at 900degreesC. The optical absorption was greatly improved by the heat-treatment due to the increase of Au particle sizes. At the heat-treatment of 900degreesC, Au/SiO2 films containing 3 to 65 vol% An showed absorption peaks at the wavelength of 540 to 560 nm, while no absorption peak was observed in the as-deposited films containing more than 12 vol% An. The intensity of the absorption peak for the Au/SiO2 films heat treated at 900degreesC increased with increasing An content, showing a maximum value around the An content of 37 vol%.