Influence of in situ annealing on carrier dynamics in InGaAs/GaAs quantum dots

The carrier dynamics in in situ annealed InGaAs quantum dots (QDs) is studied by various photoluminescence (PL) techniques. An enhancement in the PL intensity for the annealed QDs is observed only when pumping takes place below the GaAs band gap, indicating that the crystal quality of the QDs is improved, and that the carrier tunnelling from the QDs to the barrier or interface defects is negligible. The relief of the strain and the reduction of the piezoelectric field in the annealed QDs further lead to an enhancement of the overlap of electron and hole wavefunctions, which manifests itself in the shorter PL decay time governed by the radiative lifetime.