Abstract :
Copper-containing silica films were synthesized by radiofrequency (rf) co-sputtering deposition technique, and then heattreated
in different annealing atmospheres, i.e. either oxidizing or reducing, with the aim to develop suitable preparation
methodologies for controlling the composite structure. Characterization of the samples along the various preparation steps was
performed by Rutherford backscattering spectrometry (RBS), transmission electron microscopy and optical absorption
spectroscopy. The nonlinear optical coefficient n2 of the nanocomposite films was estimated by the Z-scan technique.
Experimental observations showed that copper migration and aggregation depend critically on the annealing conditions,
giving rise to quite different stable structures. In particular, for samples heat-treated first in air and then in a H2–Ar gas mixture,
the oxidizing atmosphere drives copper towards the surface while the reducing one promotes the subsequent clusterization in a
well defined region.
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