H-sensitive radiative recombination path in Si nanoclusters embedded in SiO2

The room-temperature photoluminescence (PL) from silicon nanocrystals embedded in a SiO2 matrix fabricated by electron cyclotron resonance plasma-enhanced chemical vapor deposition and subsequent annealing in Ar and (Ar+5%H2) was studied. In addition to strong increases of the integrated PL intensity (factors of ∼4 to 10), the selective enhancement of contributions to the PL spectra at long wavelengths was observed for (Ar+5%H2) annealings. The selective H passivation of Si dangling bonds in disordered Si nanoclusters where radiative recombination proceeds through disorder-induced shallow states is proposed as a possible explanation for the observed effects.