Effect of well confinement on photoluminescence features from silicon nanoparticles embedded in an SiC/SiNx multilayered structure

Light emission from a quantum well-dot structure comprising amorphous Si nanoparticles (similar to 1.4 nm) embedded in SiC/SiNx multilayers (a few tens nm thick for individual sublayers) was investigated. Strong blue-green photoluminescence was measured at room temperature on the as-deposited samples and the spectral profile shows some markedly modulated features. It displays flattened profiles of roughly equal intensity when silicon particles in both nitride and carbide sublayers can be effectively excited, whereas when the nitride sublayer is less effectively activated at longer excitation wavelength the photoluminescence is pinned (here at 500 nm), showing a rather narrow, slowly decreasing profile. The phenomenon of narrowed emission is also observed in the Si-in-SiC multilayer consisting of particles of varying size distributions. Resonance energy transfer processes among particles modified by carrier confinement may provide a reasonable explanation.