Symmetry breaking via alloy disorder to explain radiative Auger transitions in self-assembled quantum dots

Abstract

The optical spectrum of a quantum dot is typically dominated by the fundamental transition between the lowest-energy configurations. However, the radiative Auger process can result in additional redshifted emission lines. The origin of these lines is a combination of Coulomb interaction and symmetry breaking in the quantum dot. In this paper, we present measurements of such radiative Auger lines for a range of InGaAs/GaAs self-assembled quantum dots. We account for the Auger lines with a tight-binding model with a configuration interaction including symmetry breaking via alloy disorder. We show that the model accounts for the intensities of the Auger lines and the changes from quantum dot to quantum dot. We relate our findings to group theory explaining how the reduction in symmetry caused by alloy disorder is essential for the appearance of the radiative Auger lines.