Er and Cu codoped SiO2 films obtained by sputtering deposition: enhancement of the rare earth emission at 1.54 μm mediated by metal sensitizers

The modification of the Er3+ emission properties by means of the interaction with metallic species is the object of this paper. In particular, this research has evidenced the enhancement of the characteristic Er ion emission at 1.54 microns after copper incorporation in Er-doped SiO2 films deposited by RF magnetron sputtering. Metal sensitizer nature was studied by evaluating the impact of the sputtering deposition conditions, together with during- and post-deposition energetic treatments, on the structural and optical properties of the synthesized films. Since the rare earth sensitization occurrence is strictly dependent on the metal clustering state, the reported results suggest that 1.54 microns PL enhancement is achieved after copper incorporation, but preventing the formation of crystalline clusters with size larger than 1 nm. Concerning the mechanism involved in the sensitization process, it is argued that this phenomenon is due to an energy transfer process mediated by Cu-related sensitizers, that can be photostimulated even at frequencies non-resonant with the Er absorption lines in the visible range. The comparison of the estimated Er ion excitation cross section between the Er-doped and the Er and Cu codoped systems has revealed a real enhancement of this parameter when the Cu-mediated sensitization occurs.