Resonantly Excited Time-Resolved Photoluminescence Study of Self-Organized InGaAs/GaAs Quantum Dots

Relaxation and capture processes in self-organized InGaAs/GaAs quantum dots (QDs) are studied by time-resolved photoluminescence spectroscopy under resonant excitation. Relaxation between the lowest confined states is shown to be strongly suppressed indicating a pronounced phonon bottleneck effect. In neutral QDs correlated relaxation processes dominate: exciton relaxation between low lying states and Auger-type processes for higher excited states, the latter providing an efficient means to populate the ground state upon non-resonant excitation. The relaxation-limited dynamics is attributed to the disk-like shape of the investigated QDs, suggesting the control of structural properties as possible pathway to device optimization.