Picosecond dynamics of photoexcited carriers in interacting silicon nanocrystals

Highlights: • A unique set of well-defined size-controlled Si nanocrystals separated by SiO₂ barriers of different thickness was prepared by a so called superlattices approach. • The picosecond carrier recombination rate was measured directly by femtosecond pump and probe technique. • The effect of inter-nanocrystal separation on the charge carrier recombination was measured and discussed. • The Auger type recombination rate was found to be an exponentially decreasing function of the barrier thickness. - Abstract: The non-radiative Auger carrier recombination plays an important role in physics and the application of semiconductor nanocrystals. Here we report on the effect of inter-nanocrystal carrier interaction on Auger recombination. We prepared a special set of samples containing silicon nanocrystals embedded in silicon oxide with well-defined geometry. The picosecond carrier recombination rate measured by femtosecond pump and probe technique was found to be strongly dependent on the inter-nanocrystal separation. The observed decrease of the decay rate with nanocrystal separation on the nanometer scale is interpreted in terms of the wave function overlap appearing in the relevant matrix element describing the recombination process.