Metal nanocluster formation in silica films prepared by rf-sputtering: an experimental study

Composite silica films containing metal nanoclusters were prepared by the rf- sputtering technique, in which SiO2 was co-deposited with gold+copper, gold+silver, or copper+silver. The formation of either pure or alloy clusters was studied by extended X-ray absorption fine structure spectroscopy and transmission electron microscopy. For all systems, the presence of alloy aggregates was evidenced. Moreover, small amounts of pure metal aggregates as well as dispersed or oxidized dopants were observed.