On the photoluminescence from Si nanocrystals in Er-doped silica by a double-pulse technique

The mechanism of photoluminescence (PL) from Si nanocrystals (Si-nc's) in Er-doped silica is investigated by a double-pulse technique. It is shown that the decay time and the spectral intensity of PL emission from Si-nc's do not change when Si-nc's are reexcited by a delayed pulse in the presence of still excited Er ions. Results are compatible with a strong quenching of photoexcited Si-nc's through trap states and/or Auger-like interaction between Si-nc's and Er ions, both in the excited states, while PL emission originates from excitonic recombination in Si-nc's that do not couple to Er3+.