Correlation between room temperature luminescence and energy-transfer in Er–Au co-implanted silica

We report on the room temperature photoluminescence characterization in the visible and near-infrared range of Er–Au co-implanted silica systems as a function of the annealing temperature. Besides the characteristic Er³⁺ emission at 1540 nm, the samples exhibit luminescence bands in the wavelength region 600–1400 nm related to the formation of ultra-small Au_N aggregates with a number of atoms N less than 50 atoms. In particular, the correlation between such Au_N-related luminescence and the enhancement of the Er³⁺ emission was investigated and an anti-correlation between the Er³⁺ luminescence at 1540 nm and an Au_N-related band at 980 nm was revealed that represents a possible path for the energy-transfer from Au_N nanoclusters to Er³⁺ ions, giving rise to the Er³⁺ sensitized emission.