  The exciton states in strained (In,Ga)As nanorings embedded in a GaAs matrix
are computed. The strain distribution is extracted from the continuum
mechanical model, and the exact diagonalization approach is employed to compute
the exciton states. Weak oscillations of the ground exciton state energy with
the magnetic field normal to the ring are an expression of the excitonic
Aharonov-Bohm effect. Those oscillations arise from anticrossings between the
ground and the second exciton state and can be enhanced by increasing the ring
width. Simultaneously, the oscillator strength for exciton recombination
exhibits oscillations, which are superposed on a linear increase with magnetic
field. The obtained results are contrasted with previous theoretical results
for 1D rings, and differences are explained to arise from different confinement
potentials for the electron and the hole, and the large diamagnetic shift
present in the analyzed type-I rings. Furthermore, our theory agrees
qualitatively well with previous photoluminescence measurements on type-II
InP/GaAs quantum dots.
