Low energy shifted photoluminescence of Er3+ incorporated in amorphous hydrogenated silicon–germanium alloys

Abstract Low energy shifted photoluminescence from isolated erbium ions incorporated into a-SiGe:H thin films is reported. The Er 3+ are thermally diffused from an a-SiGe:H:Er layer to a-SiGe:H subsequently grown, both by magnetron sputtering. The photoluminescence observed is associated with transitions produced by erbium emission centers activated by the oxidation in a 1 h annealing process in air at 250 °C. The resultant Er 3+ concentration observed from the a-SiGe:H is affected by the hydrogen concentration already present in the layer. It is observed that at higher hydrogen concentrations in a-SiGe:H the resultant amount of diffused Er 3+ decreases. As a consequence of the resultant smaller density of erbium ions, the probability of having isolated Er 3+ ions increases. In this last regime, a correlation with stronger photoluminescence is observed.