Distribution of exciton emission linewidth observed for GaAs quantum dots grown by droplet epitaxy

We report on the exciton emission linewidth of self-assembled GaAs/AlGaAs quantum dots grown by droplet epitaxy. We applied stabilized single-photon Fourier spectroscopy to accurately evaluate the exciton linewidth of single quantum dots and found an extremely large distribution of the linewidth ranging from 40 to 400μeV at 4 K. Even the smallest linewidth is not lifetime limited and no correlation was observed between the linewidth and the exciton emission energy. These results are consistent with our previous observation of the strong correlation between the carrier dynamics in the barrier layer and the exciton linewidth of the quantum dots, and imply that the linewidth is not an intrinsic property of genuine quantum dots, but a consequence of their local environment, which can be explained by fluctuating Stark shift caused by photo-excited charged carriers.