Strong exciton-erbium coupling in Si nanocrystal-doped SiO2

Silicon nanocrystals were formed in SiO2 using Si ion implantation followed by thermal annealing. The nanocrystal-doped SiO2 layer was implanted with Er to a peak concentration of 1.8 at. %. Upon 458 nm excitation the sample shows a broad nanocrystal-related luminescence spectrum centered around 750 nm and two sharp Er luminescence lines at 982 and 1536 nm. By measuring th e excitation spectra of these features as well as the temperature-dependent intensities and luminescence dynamics we conclude that (a) the Er is excit ed by excitons recombining within Si nanocrystals through a strong coupling mechanism, (b) the Er excitation process at room temperature occurs at a s ubmicrosecond time scale, (c) excitons excite Er with an efficiency > 55%, and (d) each nanocrystal can have at most similar to 1 excited Er ion in it s vicinity. (C) 2000 American Institute of Physics. [S0003-6951(00)03517-8] .