Electronic structure and phonon-assisted luminescence in self-assembled quantum dots

Abstract

We present photoluminescence (PL) measurements on an ensemble of InAs/GaAs self-assembled quantum dots embedded in GaAs. We observe a transition from an inhomogeneously broadened photoluminescence band under non-resonant excitation into up to five phonon-assisted bands under selective excitation. We interpret the phonon-assisted PL as being indicative of an enhanced electron-phonon interaction. We also perform theoretical calculations of the single-particle energy spectrum of self-assembled quantum dots, in the framework of the single-band effective-mass approximation for electrons and using the Luttinger Hamiltonian for holes. Finally, by taking advantage of the computed wave functions we evaluate the Huang-Rhys parameter: We find an enhancement of the electron-phonon interaction that partially accounts for the experimental results.