Optical memory effects in near-surface InAs/GaAs quantum dots having sharp electronic shells

Self-assembled quantum dots (QDs) capped with less than ~10 nm display optical memory effects lasting over a time-scale of several minutes. The interaction and charge transfer between zero-dimensional states and surface states are studied using near-surface QD ensembles with well-defined electronic shells. The influence of the temperature and cap thickness have been investigated. The inhomogeneous broadening of self-assembled InAs/GaAs QDs increases from ~30 meV to more than ~46 meV as the distance of the QDs from the surface is changed from 100 nm 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