AUGER AND COULOMB CHARGING EFFECTS IN SEMICONDUCTOR NANOCRYSTALLITES

Theoretical and experimental results are presented providing evidence for fast Anger recombination in silicon nanocrystallites. Calculations give nonradiative lifetimes in the 1 ns range. Luminescence experiments on porous silicon exhibit a saturation at high excitation power. The Anger effect gives a natural explanation for this saturation as well as for the recently observed quenching of the photoluminescence and voltage tunable electroluminescence. In this last case the importance of Coulomb charging effects is shown to be at the origin of the linewidth. The consequences of such fast Auger recombination for the optical efficiency of indirect band-gap semiconductor nanocrystallites are discussed.