Optical spectroscopy of carrier relaxation processes in Si nanocrystals

We have investigated thermalization, trapping and recombination processes of carriers in Si nanocrystals embedded in a SiO2 matrix. The study has been performed using time-resolved optical techniques of photoluminescence and induced absorption, allowing for 17 ps and 150 fs resolution, respectively. Based on these results, the possible relaxation processes are discussed. Special attention is paid to cooperative processes circumventing the effect of phonon bottleneck theoretically expected for Si nanocrystals.