Carrier relaxation in (GaIn)As quantum dots

Time-resolved photoluminescence experiments are performed to study carrier relaxation in strain-induced (GaIn)As quantum dot structures. We observe a sub-picosecond onset of the photoluminescence from the lowest quantum-dot electron–hole transition after optical excitation of higher-energetic barrier states. This shows that carrier capture into the quantum-dot ground state can be extremely fast at high electron–hole densities. The recombination lifetime of the lowest quantum-dot transition and the interlevel relaxation time are extracted from the decay of the photoluminescence transients.