Enhanced fraction of coupled Er in silicon-rich silicon oxide layers grown by magnetron co-sputtering

The structural and optical emission properties of Er-doped silicon-rich silica layers containing 1021 at cm−3 of erbium are studied as a function of deposition conditions and annealing treatment. Magnetron co-sputtering of three confocal targets (Si, SiO2 and Er2O3) under a plasma of pure argon was used to deposit the layers at 500 °C. The silicon excess was varied in the layers in the range 7–15 at% by monitoring the power applied on Si cathode. The as-grown samples were found significantly emitting at 1.54 μm under non-resonant excitation. A maximum Er emission was observed after annealing at a moderate temperature (600 °C) for any amount of Si excess, with a highest 1.54 μm photoluminescence (PL) from the sample containing 13 at% of Si. While no nanocrystals were observed in the samples annealed at 600 °C, the sensitizers might, therefore, consist in ‘atomic’ scaled entities (Si agglomerates, for example) considered in recent similar work. The comparison of the emission features of our “best” sample and their counterparts reported so far, shows that the approach used this work allows to increase the fraction of the Er3+ ions coupled to Si sensitizers from 3% up to 12% of the total Er content.