Quantum confinement in MOVPE-grown structures with self-assembled InAs/GaAs quantum dots

In this communication we report on low-temperature, micro-photoluminescence study of quantum confinement in MOVPE-grown structures with InAs/GaAs quantum dots (QDs) with GaAs and/or strain reducing InGaAs/GaAs capping. We focus our attention on sharp emission lines, which appear in both structures at energies up to 80 meV below the wetting line emission. Power-dependent measurements confirmed their attribution to single excitons as well as biexcitons. Negative binding energy of biexcitons with systematic dependence on their energy was observed. It has been proposed that the investigated emission lines result from radiative recombination in flat non-fully developed QDs in the investigated structure. The attribution is confirmed by transmission electron microscopic analysis of investigated structures.