Quantum interference due to continuum states in single self-assembled quantum dots

Summary form only given. The study of quantum mechanical interactions between excited carriers in the semiconductor quantum dots (QDs) provides better understanding of zero-dimensional (0D) systems. One of the remarkable features of QDs is their atomic like density of states (DOS). Recently, we performed single dot spectroscopy on InGaAs self-assembled quantum dots (SAQDs) grown by Stranski-Krastnow mode, and found that their photoluminescence excitation (PLE) spectra exhibit 2D-like continuum states as well as discrete DOS structures. Because SAQDs are connected with 2D wetting layer (WL), it is supposed that the observed continuum originate from a crossover from 0D to 2D nature in their DOS. On the other hand, excited carriers in a single discrete state within a continuum show asymmetric resonance in their optical spectrum. This asymmetry is produced by interference between the optical transitions of a discrete energy state with continuum, the so-called Fano interference. In this paper, we carried out PLE spectroscopy with high excitation power and observed asymmetric resonances due to the existence of continuum states.