Temperature-Dependent Exciton Dynamics in a Single GaAs Quantum Ring and a Quantum Dot

Micro-photoluminescence was observed while increasing the excitation power in a single GaAs quantum ring (QR) at 4 K. Fine structures at the energy levels of the ground (N = 1) and excited (N = 2) state excitons exhibited a blue shift when excitation power increased. The excited state exciton had a strong polarization dependence that stemmed from the asymmetric localized state. According to temperature-dependence measurements, strong exciton-phonon interaction (48 meV) was observed from an excited exciton state in comparison with the weak exciton-phonon interaction (27 meV) from the ground exciton state, resulting from enhanced confinement in the excited exciton state. In addition, higher activation energy (by 20 meV) was observed for the confined electrons in a single GaAs QR, where the confinement effect was enhanced by the asymmetric ring structure.

Automated summary

Micro-photoluminescence in a single GaAs quantum ring was observed, with a blue shift in the energy levels of the ground and excited state excitons as the excitation power increased. The excited state exciton exhibited strong polarization dependence due to an asymmetric localized state. Temperature-dependence measurements revealed a stronger exciton-phonon interaction in the excited state compared to the ground state, resulting from enhanced confinement. Additionally, confined electrons in the asymmetric ring structure of the single GaAs quantum ring exhibited a higher activation energy.