Exciton Dynamics in Stacked InGaAs/GaAs Quantum Rings Under Resonant Excitation

We report systematic temperature-dependent measurements of photoluminescence spectra in self-assembled InGaAs/GaAs quantum rings (QRs) under resonant excitation condition. We have studied the rise in temperature of the ground-state intensity. The carrier transfer between the ground state of the small ring family towards the big-ring family of the bimodal size distribution is identified by analyzing the photoluminescence spectra. This effect is observed in very thin spacer and under resonant excitation. This situation makes important the lateral tunneling of excitons between rings under low temperatures (10 K). Tunneling time about 1ns was estimated at low temperature and compared to similar carrier transfer in quantum dots (QDs) found in the literature.