Energy transfer between amorphous Si nanoclusters and Er3+ ions in a SiO2 matrix

We report on the energy-transfer mechanism between amorphous Si nanoclusters and erbium ions in a SiO2 matrix. We have studied a set of optimized samples which show maximum Er3+ to Si-nc coupling ratio. We demonstrate that the transfer mainly occurs to the I-4(11/2) level in less than 100 ns and that higher Er3+ energetic levels are not involved. Furthermore, we show that there are no traces of Auger back-transfer, excited state absorption, or pair-induced quenching mechanisms in our samples, leading us to propose a model in which the short interaction distance between Si-nc and Er3+ ions is the limiting factor for the noncomplete excitation of the whole Er3+ active population.