Study of the energy transfer mechanism in different glasses co-doped with Si nanoaggregates and Er3+ ions

In the past few years the incorporation of Si nanocrystals in Er doped silica was found to strongly enhance the infrared luminescence of Er3+ at 1.54 mu m as a consequence of an energy transfer process. This has important implications in the optoelectronic field, in particular for the realization of planar waveguide optical amplifiers. To this respect, multi-component glasses can offer better performances than silica in terms of Er solubility and band broadness. In this work we investigate the energy transfer mechanism in different glass hosts: common silica (S), aluminosilicate (L) glass and soda-lime (H) glass. Si and Er have been co-implanted in the substrates and post implantation thermal treatments have been performed to promote Si aggregation. The most intense Er3+ PL emission at 1.54 mu m was achieved after a thermal treatment at 400 degrees C for the L substrate and at 600 degrees C for the H substrate. Such emission was investigated in a wide range of excitation wavelengths (300-800 nm), showing a very efficient energy transfer process for all of the substrates. These results together with structural investigation allowed to evidence that the same kind of mechanism occurs in the different hosts. Our results based on Energy Filtered TEM suggest that good energy transfer mediators are small Si aggregates and not necessarily crystalline clusters. (c) 2004 Elsevier B.V. All rights reserved.