Mechanism of bright red emission in Si nanoclusters

Abstract

A bright photoluminescence around 1.7 eV is observed for post-annealed samples of 1 MeV Si²⁺ implanted in an SiO₂ matrix. A super-linear power dependence of photoluminescence intensity accompanied by pulse shortening under continuous wave laser excitation is recorded without any spectral narrowing. An emission process comprised of an initial non-radiative recombination (time constant ~280-315 ps) of excited carriers in the defect states in SiO₂ matrices to the conduction band minima of nc-Si, followed by a slower process of radiative recombination in the direct band transition for nc-Si along with a non-radiative Auger recombination (time constant ~2.67 ns) is proposed.