Annealing effect on the photoluminescence of Ge-doped silica films

SiO2 thin films doped with Ge nanocrystals (NCs) were grown using the RF-sputtering technique. X-ray diffraction studies revealed a diamond structure for Ge NCs. The presence of Ge NCs in the grown films was also confirmed by Raman spectroscopy. Photoluminescence spectroscopy of the samples revealed an emission band at 2.07 eV, which is tentatively attributed to defects located at the Ge-matrix interface. This was found to be quite sensitive to variations of local matrix composition, induced by the annealing process.