The evolution of photoluminescence from Si cluster to nanocrystal in Si-rich oxide/SiO2 multilayer films

Abstract

The evolution of photoluminescence (PL) from Si cluster to nanocrystal in Si-rich oxide (SRO)/SiO2 multilayer films is reported. Two PL bands can be obtained when the SRO layer thickness is no larger than 2 nm, and the high energy PL band (blue band) is related to the interband transition of Si cluster caused by quantum confinement effect (QCE), while the low energy band (red band) is related to the interface recombination. Both Si clusters and nanocrystals exist in the film when the SRO layer is increased to 3 nm, and the intense PL in the red band suggests that Si nanocrystals becomes the main light-emitting centers. The blue band disappears when the SRO layer is increased to 4 nm, and the PL mechanisms of the red band are QCE and interface defects in Si nanocrystals.