Frohlich interaction in InAs/GaAs self-assembled quantum dots - art. no. 075303

The phonon bottleneck in self-assembled InAs/GaAs quantum dots (SAD's) is o bserved directly in continuous-wave photoluminescence experiments when exci ting one GaAs longitudinal optical (LO)-phonon energy above the ground leve l of the smallest dot. To overcome the phonon bottleneck, selective photolu minescence (PL) experiments are performed and multiple phonon-assisted radi ative bands are observed. We found that no real crystal states are involved in the experimentally observed phonon emission. Under nonresonant excitati on at 5 K, the SAD's photoluminescence band is centered at 1.315 eV. As pro ven by our photoluminescence experiments at high excitation densities, ther e are no excited states in such small dots. We interpret the phonon-assiste d PL as being due to enhanced Frohlich interaction between strain-induced p olarized excitons in the SAD's and LO phonons. Further experimental support for this model is found from the cleaved-side PL measurements. A light-hol e ground state is observed, instead of the theoretically predicted heavy-ho le one.