Asymmetric Stark shift in AlxIn1−xAs/AlyGa1−yAs self-assembled dots

Abstract

We present microphotoluminescence measurements of self-assembled quantum dots subject to an electric field applied along the growth axis. The spectra reveal sharp peaks corresponding to a number of “single-dot” emission lines. An asymmetric Stark shift as a function of applied field is obtained; for positive fields (electron pushed towards the apex of the dot), an initial blueshift is measured, followed by saturation and eventually a small redshift for stronger positive fields, while a continuous redshift is observed for negative field values. High positive fields also give rise to structural changes in the emission spectra as lines are enhanced or quenched under the influence of the field. The field dependence of the emission lines are reproduced in our theoretical calculations, which show that the asymmetric Stark shift is caused by the combination of dot geometry and strong lateral confinement.