Emission intermittency in silicon nanocrystals

We present detailed results of blinking studies on individual silicon nanocrystals. The experiments show, that similar to II-VI semiconductor nanocrystals, the blinking process obeys a power law statistics. An excitation intensity dependence of the power law exponent is found for the off time probability distribution. The intensity dependence is interpreted in terms of an intensity dependent tunneling rate due to Auger assisted processes. Further we demonstrate a relation of the off time distribution to the bleaching and recovery of the emission of nanocrystal ensembles, which gives further insight in the blinking behavior according to ensemble studies. The experimental data is discussed in terms of two alternative blinking models. Evidence is provided for the existence of self-trapped polaron-like states for the ejected charge.