The change of the surface morphology and optical properties during the heat-treatment for silver films deposited on silicas

Abstract

Nanosized silver particles generated by the evaporation-condensation method were deposited on the silica glass substrate or sol-gel derived silica film to form films, which were annealed at 100 to 500°C. The surface morphology and optical absorption spectrum of the films thus obtained were observed. Furthermore, nonlinear optical properties of them were estimated using Z-scan technique. Absorption spectrum exhibited a peak due to localized surface plasmon resonance (LSPR), which was drastically shifted toward shorter wavelength side after annealing at 200°C accompanying with the changing of the surface morphology. The nonlinear refractive index, 7, of silver films was negative, and its absolute value was decreased with increasing the annealing temperature. The largest contribution of LSPR resulted in the enhancement of 7 when annealed at 100°C. © 2005 The Surface Science Society of Japan.