Universal Size-Dependent Trend in Auger Recombination in Direct-Gap and Indirect-Gap Semiconductor Nanocrystals

We report the first experimental observation of a striking convergence of Auger recombination rates in nanocrystals of both direct- (InAs, PbSe, CdSe) and indirect-gap (Ge) semiconductors, which is in contrast to a dramatic difference (by up to 4-5 orders of magnitude) in the Auger decay rates in respective bulk solids. To rationalize this finding, we invoke the effect of confinement-induced mixing between states with different translational momenta, which diminishes the impact of the bulk-semiconductor band structure on multiexciton interactions in nanocrystalline materials.