Self-Assembly of Symmetric GaAs Quantum Dots on (111)A Substrates: Suppression of Fine-Structure Splitting

Great suppression of fine-structure splitting (FSS) is demonstrated in self-assembled GaAs quantum dots (QDs) grown on AlGaAs(111)A surface. Due to the three-fold rotational symmetry of the growth plane, highly symmetric excitons with significantly reduced FSS are achieved. Scanning tunneling microscopy and cross-sectional transmission microscopy demonstrate a laterally symmetric dot shape with abrupt interface. Polarized photoluminescence spectra confirm excitonic transition with FSS smaller than ∼20 µeV, a substantial reduction from that of QDs grown on (100).