Near-surface InAs/GaAs quantum dots with sharp electronic shells

The interaction between zero-dimensional states and surface states is studied using near-surface quantum dot (QD) ensembles with well-defined electronic shells. The inhomogeneous broadening of self-assembled InAs/GaAs QDs increases from ∼30 to more than ∼46 meV as the distance of the QDs from the surface is changed from 100 to 5.0 nm. Simultaneously, a decrease of the radiative recombination intensity by ∼3 orders of magnitude, and a red-shift of ∼65 meV are observed. For QDs capped with less than ∼10 nm, remarkable charge transfers between the QD and surface states lead to optical memory effects lasting over time-scales of several minutes.