Line broadening of excitonic complexes in self‐assembled GaAs/AlGaAs single quantum dots

We present a detailed experimental study of the line broadening of the different excitonic complexes inside single GaAs/AlGaAs quantum dots. The investigated nanostructures are self assembled quantum dots (QDs), strain free nanocrystals grown by Modified Droplet Epitaxy technique. They show a typical PL spectrum with a triplet structure and by time correlated spectroscopy each contribution can be unambiguously assigned to neutral exciton, biexciton and trion. By high resolution spectroscopy, we have studied the line broadening for several single GaAs/AlGaAs QDs. The measured linewidth is found to vary between several tens to few hundreds of meV and we attribute this to spectral diffusion. The striking feature of the PL spectrum is that the trion and the biexciton line are always sharper with respect to the neutral exciton (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)