Photoluminescence Degradation and Passivation Mechanisms of Si Nanoclusters in Silicon Oxide Matrix

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The Si nanoclusters embedded in a silicon oxide matrix were prepared using a laser-assisted chemical vapor deposition (LACVD) system. A degradation of photoluminescence (PL) by irradiating the sample with helium–cadmium (He–Cd) laser was observed. The dependence of PL degradation on long-term irradiation of He–Cd laser was investigated. We found that the He–Cd laser-induced breakage of Si–H-related bonds resulted in the formation of Si dangling bonds such as D centers and Pb centers, which are known to decrease PL intensity. The PL intensity of He–Cd laser-irradiated samples can be increased to that of as-deposited samples after exposing the samples to a H2 ambient at 400°C for 5 min. Post annealing in H2 could also help increase PL intensity by passivating the defect centers in as-deposited samples.