Phonon sidebands in exciton and biexciton emission from single GaAs quantum dots

We report on the observation of asymmetric phonon sidebands on both the exciton and biexciton emission lines in single GaAs monolayer fluctuation quantum dots. The contribution of phonon sidebands to the emission line is larger for the biexciton than for the exciton. We model the exciton line shape by means of a nonperturbative coupling with acoustic phonons and show that energetic confinement is an important clue to understand why phonon sidebands are sometimes observed and sometimes not. Finally, we discuss the extension of our model to the biexciton case.