Heavy- and light-hole magneto-excitons bound to donor in quantum ring

We analyse the alteration of the density of states of the light- and the heavy-hole magnetoexcitons due to the presence of an impurity donor in InAs quantum ring. It is shown that the donor provides a noticeable redshift of the lower peaks of the density of states, corresponding to the vibrational states of the exciton bound to the donor, while the effect on the higher energy levels related to a relative electron-hole rotation is mainly reduced to the splitting of the twofold degenerate states. Energies dependencies on the external magnetic field, applied along the growth direction show that the exciton-donor interaction leads to the flattening of the curves of the Aharonov-Bohm oscillations of the lowest energy levels and to diminishing of their amplitudes. This effect is more pronounced for heavy-hole magneto-exciton.