  Neutral excitons in strained axially symmetric In(Ga)As/GaAs quantum dots
with ringlike shape are investigated. Similar to experimental self-assembled
quantum rings, the analyzed quantum dots have volcano-like shapes. The
continuum mechanical model is employed to determine the strain distribution,
and the single-band envelope function approach is adopted to compute the
electron states. The hole states are determined by the axially symmetric
multiband Luttinger-Kohn Hamiltonian, and the exciton states are obtained from
an exact diagonalization. We found that the presence of the inner layer
covering the ring opening enhances the excitonic Aharonov-Bohm (AB)
oscillations. The reason is that the hole becomes mainly localized in the inner
part of the quantum dot due to strain, whereas the electron resides mainly
inside the ring-shaped rim. Interestingly, larger AB oscillations are found in
the analyzed quantum dot than in a fully opened quantum ring of the same width.
Comparison with the unstrained ring-like quantum dot shows that the amplitude
of the excitonic Aharonov-Bohm oscillations are almost doubled in the presence
of strain. The computed oscillations of the exciton energy levels are
comparable in magnitude to the oscillations measured in recent experiments.
