Microstructure and emission properties of Si nanograins and Er-doped silica films obtained by reactive magnetron co-sputtering

Erbium and silicon co-doped silica films have been fabricated by reactive magnetron sputtering. A correlation is made between the microstructure monitored by the hydrogen rate rH in the plasma and the photoluminescence properties. The erbium emission at 1.54 μm is enhanced by the increase of rH while no emission due to the silicon nanograins is observed. An explanation is given by the microstructure revealed by Raman spectroscopy. Increasing rH values lead to the deposition of increasingly numerous silicon nanograins whose size decreases. The assumption is made that the nanograins absorb the laser pumping light which creates electron–hole pairs. The energy resulting from their recombination is supposed to be transferred efficiently to the erbium ions.