Fine-structure splitting reduction of ionized impurity bound exciton in quantum dot

The ground-state energy and fine-structure splitting of ionized shallow donor impurity-exciton complex in quantum dots are investigated. It is found that fine-structure splitting could be largely reduced by the off-center ionized impurities since the anisotropic shape of exciton envelope function is significantly changed. Anomalous Stark shifts of the ground-state energy and efficient tuning of the fine-structure splitting by the external electric field due to the local electric field produced by the ionized impurities are discussed. The scheme may be useful for the design of the quantum dots-based entangled-photon source.