Vertical electric field induced suppression of fine structure splitting of excited state excitons in a single GaAs/AlGaAs island quantum dots.

We report experimentally on fine structure splitting (FSS) of various excitonic transitions in single GaAs island quantum dots, formed by a monolayer thickness fluctuation in the narrow GaAs/ AlGaAs quantum well, and embedded in an n-i-Schottky diode device. By applying a forward vertical electric field (F) between the top metallic contact and the sample substrate, we observed an in-plane polarization rotation of both the ground and the excited state excitons with increasing the electric field. The polarization rotations were accompanied with a strong decrease in the FSS of the ground as well as the excited state excitons with the field, until the FSS vanished as F approached 30 kV/cm. [ABSTRACT FROM AUTHOR]