Temperature-driven local rearrangement in the Er environment of Er-doped silica glass films prepared by rf-cosputtering deposition

In this paper, an experimental study is presented on Er:SiO2 films prepared by an rf-cosputtering deposition technique, and then annealed in the 100–1200 °C range. Samples were characterized by spectrally resolved cathodoluminescence, UV–VIS photoluminescence and Rutherford Backscattering Spectrometry (RBS). Strong optical modifications with temperature were observed, connecting the peculiar features of the Er luminescence activity to those of the silica matrix, namely, the density of nonbridging oxygen hole centers, oxygen-deficient sites and OH groups. In general, a complex phenomenology was observed, involving major local rearrangements of the Er environment. RBS data allowed to evidence migration phenomena, resulting in a compositional change of the films, thus indicating the progressive modification of the system as well as the possible formation of Er nanoclusters for high temperatures.