Oxygen-passivated enhancement of photoluminescence from SiO2 films containing Si nanocrystals

SiO2 films containing Si nanocrystals were exposed to atomic oxygen (O) plasma at different temperatures. The photoluminescence intensity from the films increases with increasing exposure time, and then saturates at a level that depends on the exposure temperature. There are no significant changes in the PL spectrum shapes and the O-induced PL is fully recovered to its original state by thermal annealing. The results are likely to be due to a balance between defect passivation and depassivation, with the activation energy for the passivation reaction being larger than that for the depassivation reaction.