Ultrafast Relaxation Dynamics in Strain-Induced Quantum Dots

We perform time-resolved photoluminescence experiments to study carrier relaxation in strain-induced (GaIn)As quantum dots. A sub-picosecond onset of the photoluminescence from the lowest quantum-dot transition after optical excitation of higher-energetic barrier states is observed, which shows that carrier capture into the quantum-dot ground state can be extremely fast at high carrier densities. The recombination lifetime of the lowest quantum-dot transition and the interlevel relaxation time are extracted from the photoluminescence decay.