Location of Er atoms with respect to Si nanoclusters in luminescent Er and Si co-implanted silicates

Abstract

ABSTRACTIn this contribution we explore the structural properties of different silicate glasses c o-implanted with Si and Er ions to various doses, and see how they affect the emission properties around 1540 nm. We have used silica, soda-lime and aluminium silicates as substrates. A multiimplantation scheme provided an uniform Si excess (5 or 15%) background to the subsequently implanted Er atoms. Er peak concentration has been varied between 2×1019 cm−3 to 6×1020 cm−3. The structural analysis of the resulting structures have been performed by means of SIMS, XPS, Raman, and EFTEM.It was found that the best photoluminescence (PL) emission properties are the ones for which a phase separation between the implanted Si and the matrix occurs, even without the formation of nanocrystalline aggregates. Amorphous Si nanoclusters with average size around 3 nm (for high Si content) or below 1nm (for low Si content) have been revealed after the EFTEM analysis. By analysing the layers by EELS and HAADF we have been able to determine the location of Er atoms relative to the Si nanoclusters for the first time to our knowledge. In samples with Er concentration higher than 1020 cm−3, the Er atoms are not randomly dispersed in the matrix. On the contrary, they tend to aggregate, forming large agglomerations mostly in the regions of lower density of Si precipitates. This observation correlates with the appearance of PL quenching at concentrations around 2×1020 cm−3. A suitable tuning of the annealing temperature has been found to drastically reduce this deleterious effect.