Preparation of Au/SiO₂ nano-composite multilayers by helicon plasma sputtering and their optical properties

Au/SiO₂ nano-composite multilayers were prepared by helicon plasma sputtering. The Au particles dispersed in the SiO₂ matrix grew with increasing deposition time in the initial time less than 10 s, then changed from network-like to film-like microstructure with increasing deposition time. The optimum deposition time for preparing the Au particles was 8 s, and the size of Au particles was about 6 to 8 nm. The absorption peak due to the surface plasmon resonance of Au particles was observed at the wavelength of 560 nm in the optical absorption spectra for the as-deposited Au/SiO₂ thin films containing 3.3 to 10.3 vol%Au. The intensity of the absorption peak increased with increasing Au content, and the optimum Au content was about 10.3 vol%.