Shape‐dependent properties of self‐organized quantum dots: Few‐particle states and exciton‐phonon coupling

Abstract

AbstractThe electronic and optical properties of self‐organized InAs/GaAs quantum dots are investigated in view of the actual structural properties. Focussing on the shape we demonstrate theoretically a strong impact of the varying strain distribution on the electronic and, in particular, the exciton properites in such quantum dots. The inhomogeneous strain, typical for self‐organized quantum dots, lowers the symmetry and increases the local charge density. Resonant Raman experiments on pyramidal InAs/GaAs quantum dots show an enhance exciton–LO‐phonon coupling reflecting the strain‐induced local charge density. Experiments on single InAs/GaAs quantum dots demonstrate an unexpected strong impact of the structural properties on few‐particle complexes on the example of the biexciton complex. Anti‐binding biexciton complexes are demonstrated. The apparent correlation of the biexciton binding energy and exciton transition energy, with a transition from binding to anti‐binding at ∼1.24 eV, is attributed to a decreasing exciton localization, resulting from the finite barrier height. The Coulomb interaction with delocalized states is negligible for the energy of the localized states.