Elucidation of the surface passivation role on the photoluminescence emission yield of silicon nanocrystals embedded in SiO2

The ability of surface passivation to enhance the photoluminescence (PL) emission of Si nanocrystals in SiO2 has been investigated. No significant increase of the average nanocrystal size has been detected for annealings at 1100 degreesC between 1 min and 16 h. In contrast, the PL intensity steadily increases and reaches saturation after 3-4 h of annealing time. Such behavior shows an inverse correlation with the amount of Si dangling bonds (P-b centers) at the interface between Si nanocrystals and the SiO2 matrix. A postannealing at 450 degreesC in forming gas enhances the PL intensity and lifetime, due to a reduction in P-b concentration, without modifying the spectral shape of the PL emission. (C) 2002 American Institute of Physics.