Effects of thermal annealing on the emission properties of type-II InAs quantum dots (QDs) covered by a thin GaAs(1-x)Sb(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-x)Sb(x) layer. We find that the type-II QD structure can sustain thermal annealing up, to 850 degrees 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-x)Sb(x) type-II QDs. (C) 2009 Elsevier B.V. All rights reserved.
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PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
