Optical properties of SiO2 thin layers with Ag nanoparticles

Ag nanoclusters in a SiO2 matrix prepared by RF magnetron co-sputtering and subsequent irradiation with heavy 4.5 MeV Au+ ions were formed. The refractive index and optical absorption spectra of the films were studied. The method of the disappearing diffraction pattern was used for the refractive index determination. The refractive index enhances with increasing Ag concentration, as expected from the light scattering theory. SiO2:Ag thin films exhibit a plasmon resonance in the visible region. In the as-deposited films the Ag nanoclusters are less than 1 nm and are formed during the deposition. The intensity of the plasmon peak is low. After irradiation with 4.5 MeV Au+ ions the intensity of the peak increases and the peak becomes narrower. The TEM study shows that this related to the change in the size of the Ag nanoclusters. (C) 2002 Elsevier Science Ltd. All rights reserved.