Effects of substrate temperature and annealing in air on optical properties of Ag films prepared by thermal evaporation

Abstract

The effects of the substrate temperature and annealing in air on the structural and optical properties of Ag films have been studied. Ag films were prepared by thermal evaporation on glass substrates at different substrate temperatures (room temperature, 60 °C and 90 °C). Post-deposition annealing of the film was carried out at temperatures among 250 and 350 °C. Surface morphology of Ag film was observed by atomic force microscopy. Surface composition was detected by Raman spectra. Reflectance was measured by a double beam spectrophotometer. The results show that surface of the annealed films grown at higher substrate temperature is more oxidized. For the annealed film grown at 90 °C substrate temperature, the agglomeration seems to follow the grain boundary grooving process and size of islands increases with increasing annealing temperature. However, the annealed film grown at 60 °C substrate temperature agglomerates via nucleation of voids followed by the fractal growth of voids. It is found that the substrate temperature of the films will affect the agglomeration characteristic of the films annealed at different temperature in air, which results in the difference in the optical properties of the annealed films.