Characterization of the local charge environment of a single quantum dot via resonance fluorescence

We study the photon-statistical behavior of resonance fluorescence from self-assembled InAs quantum dots (QDs) as a function of the density of free charge carriers introduced by an above band-gap laser. Second-order correlation measurements show bunching behavior that changes with above-band laser power and is absent in purely above-band excited emission. Resonant photoluminescence excitation spectra indicate that the QD experiences discrete spectral shifts and continuous drift due to changes in the local charge environment. These spectral changes, combined with the tunneling of charges from the environment to the QD, provide an explanation of the bunching observed in the correlations.