Photoluminescence of Si from Si nanocrystal-doped SiO2/Si multilayered sample

A multilayered Si nanocrystal-doped SiO2/Si (or Si-nc:SiO2/Si) sample structure is studied to acquire strong photoluminescence (PL) emission of Si via modulating excess Si concentration. The Si-nc:SiO2 results from SiO thin film after thermal annealing. The total thickness of SiO layer remains 150 nm, and is partitioned equally into a number of sublayers (N = 3, 5, 10, or 30) by Si interlayers. For each N-layered sample, a maximal PL intensity of Si can be obtained via optimizing the thickness of Si interlayer (or dSi). This maximal PL intensity varies with N, but the ratio of Si to O is nearly a constant. The brightest sample is found to be that of N = 10 and dSi = 1 nm, whose PL intensity is ∼5 times that of N = 1 without additional Si doping, and ∼2.5 times that of Si-nc:SiO2 prepared by co-evaporating of SiO and Si at the same optimized ratio of Si to O. Discussions are made based on PL, TEM, EDX and reflectance measurements.