Mechanisms of Auger recombination in semiconducting quantum dots

Microscopic calculation of the probability of Auger recombination of charge carriers localized in a semiconducting quantum dot (QD) is carried out. It is shown that two mechanism of Auger recombination (nonthreshold and quasi-threshold) operate in the QD. The nonthreshold Auger recombination mechanism is associated with scattering of a quasimomentum from a heterobarrier, while the quasi-threshold mechanism is connected with spatial confinement of the wave functions of charge carriers to the QD region; scattering of carriers occurs at the short-range Coulomb potential. Both mechanisms lead to a substantial enhancement of Auger recombination at the QD as compared to a homogeneous semiconductor. A detailed analysis of the dependence of Auger recombination coefficient on the temperature and QD parameters is carried out. It is shown that the nonthreshold Auger recombination process dominates at low temperatures, while the quasi-threshold mechanism prevails at high temperatures. The dependence of the Auger recombination coefficient on the QD radius experiences noticeable changes as compared to quantum wells and quantum filaments.