Asymmetry of localised states in a single quantum ring: polarization dependence of excitons and biexcitons

TL;DR

This study investigates the polarization-dependent properties of excitons and biexcitons in a single anisotropic GaAs quantum ring, revealing asymmetries in localized states and their effects on emission energies and selection rules.

Contribution

It provides new insights into the polarization dependence of excitonic states in anisotropic quantum rings, highlighting asymmetry effects on energy splitting and oscillator strengths.

Findings

Large energy difference (0.8 meV) for perpendicular polarizations in exciton emission.

Biexciton shows twice the energy difference compared to exciton for perpendicular polarizations.

Possible change in selection rules due to lowered symmetry in the quantum ring.

Abstract

We performed spectroscopic studies of a single GaAs quantum ring with an anisotropy in the rim height. The presence of an asymmetric localised state was suggested by the adiabatic potential. The asymmetry was investigated in terms of the polarization dependence of excitons and biexcitons, where a large energy di erence (0.8 meV) in the exciton emission energy for perpendicular polarizations was observed and the oscillator strengths were also compared using the photoluminescence decay rate. For perpendicular polarizations the biexciton exhibits twice the energy di erence seen for the exciton, a fact that may be attributed to a possible change in the selection rules for the lowered symmetry.