Abstract:
This review is devoted to the mechanisms of Auger recombination in semiconductor nanoheterostructures. A distinc- tive feature of nanoheterostructures is strong spatial heterogeneity caused by existence of heterogeneous boundaries. Heterogeneities have a fundamental effect on the energy value and behavior of charge carrier wave functions in quantum-dimensional heterostructures, and, as shown in this review, the heterogeneity significantly affects the macroscopic properties of semiconductor nanostructures. The presence of a heterogeneous boundary affects the electron-electron (hole-hole) interaction in quantum structures, and this effect is fundamental. The heterogeneity removes the restrictions imposed on interelectronic collision processes by the laws energy and momentum of conservation, which leads to the appearance of thresholdless Auger recombination channels, which depend weakly on temperature. The main mechanisms of Auger recombination of nonequilibrium charge carriers in semiconductor heterostructures with quantum wells (Part 1), quantum filaments, and quantum dots (Part 2) are considered. It is shown that there are three fundamentally different Auger recombination mechanisms: thresholdless, quasi-threshold, and threshold processes. The speed of the thresholdless process has weak temperature dependece. The threshold energy of the quasi-threshold process significantly depends on the width of the quantum well and is close to zero for narrow quantum wells. It is shown that thresholdless and quasi-threshold Auger processes prevail in narrow quantum wells, while threshold and quasi-threshold Auger processes prevail in wide quantum wells. The critical width of the quantum well is found at which the quasi-threshold Auger recombination channel transforms into a three-dimensional threshold Auger process. The influence of phonons on Auger recombination processes in quantum wells is also analyzed. It is shown that for narrow quantum wells, the Auger process involving phonons becomes resonant, which leads to an increase in the Auger recombination coefficient taking into account phonons. The effect of relaxation processes on Auger recombination mechanisms in homogeneous semiconductors is considered separately. It is shown that taking into account relaxation processes leads to disappearance of the energy threshold for Auger recombination processes.
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