Tailoring of the wave function overlaps and the carrier lifetimes in InAs/GaAs_1-xSb_x type-II quantum dots

Effects of thermal annealing on the emission properties of type-II InAs quantum dots (QDs) covered by a thin GaAs_1-xSb_x layer are investigated by photoluminescence (PL) and time-resolved PL measurements. Apart from large blueshifts and a pronounced narrowing of the QD emission peak, the annealing induced alloy intermixing also leads to enhanced radiative recombination rates and reduced localized states in the GaAs _1-xSb_x layer. We find that the type-II QD structure can sustain thermal annealing up to 850 °C. In particular, we find that it is possible to manipulate between type-I and type-II recombinations in annealed QDs by using different excitation powers. We demonstrate that postgrowth thermal annealing can be used to tailor the band alignment, the wave function overlaps, and hence the recombination dynamics in the InAs/GaAs_1-xSb _x type-II QDs.