Postgrowth intermixing of strain engineered InAs/GaAs quantum dots

Highlights: • The InAs QDs in a pure GaAs matrix are more sensitive to the RTA temperature allowing the highest emission energy blueshift. • Reducing of the intermixing degree by using DWELL structure. • In segregation and accumulation in the InGaAs underlying layer alter the structural and morphological properties of the QDs. • The intermixing is found to be partially prohibited for QDs grown on InGaAs strain reducing layer. - Abstract: This paper reports on the evolution of InAs/GaAs quantum dots' (QDs) intermixing process depending on the QD position with respect to the InGaAs strain reducing layer. The postgrowth intermixing has been ensured by rapid thermal annealing (RTA) at different temperatures and the processed samples were investigated by photoluminescence (PL) spectroscopy. The reference sample, containing InAs QDs in pure GaAs matrix, demonstrates the highest intermixing degree with an emission energy blueshift up to 300 meV. The reduction of the strain around the QDs for dot-in-well (DWELL) structure has been found to slightly reduces the intermixing degree leading to less emission energy blue shift. However, for the QDs with InGaAs underlying layer, a relative prohibition of the intermixing has been found to occur testifying the existing of thermally stable extended defects