Observation of Overhauser shift in a self-assembled InAlAs quantum dot

We report the polarization-dependent energy shift of excitonic emission in a self-assembled InAlAs/AlGaAs quantum dot (QD). The energy shift is well known as Overhauser shift and was observed in a naturally formed GaAs QD using monolayer fluctuation of a quantum well. However, there has been no observation so far in a self-assembled QD, which is suitable for formation of vertically coupled QDs. We demonstrate that the magnitude of the Overhauser shift is enhanced by the photo-injection of the highly polarized electron and is controllable by the polarization of the excitation light in a self-assembled InAlAs QD.