Excitation of Tm3+ by resonant energy transfer from Si nanocrystals

Photoluminescence (PL) properties and PL decay dynamics of SiO2 films containing Si nanocrystals (nc-Si) and Tm3+ were studied. The samples exhibited a broad PL at around 1.5 eV due to the recombination of excitons in nc-Si, and rather sharp PL at 1.58, 0.84, and 0.69 eV corresponding to the intra-4f shell transitions of Tm3+. The correlation between the intensities of nc-Si and Tm3+ related PL was studied as a function of the Tm concentration, the size of nc-Si, and the temperature. It was found that the intensity of Tm3+ related PL depends strongly on the size of nc-Si. At low temperatures, the spectral shape of nc-Si PL was strongly modified by doping Tm. From analysis of the modified spectral shape, a resonant energy transfer from nc-Si to Tm3+ is discussed.