Photoluminescence in dense ensembles of silicon nanocrystals: role of concentration and mean size

Monte Carlo simulation of the luminescence kinetics was carried out for planar dielectric structures contained more than 10$^6$ Si nanocrystals. It was shown that energy transfer becomes important in closely packed nanocrystal ensembles. In this case small nanocrystals drop out of the luminescence, and the overall luminescence intensity appreciably decreases. Also, stretched exponential decay of the ensemble luminescence intensity has been demonstrated, which is caused by a dominance of one or another of the relaxation processes at different stages of the system evolution.