Excitonic Aharonov-Bohm effect: Unstrained versus strained type-I semiconductor nanorings

Abstract

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.

30-bandk·pmodel of electron and hole states in silicon quantum wells

“…1. For k z beyond the X point the dispersion relations of all bands should be mirror symmetric to the dispersion relations left of the X point, 34,35 such as the ones shown by the dashed lines in Fig. 1.…”

Aharonov-Bohm oscillations in the magnetic moment of multielectron randomly doped semiconductor cylindrical core-shell nanowires

“…12-17) have stimulated theoretical and experimental studies of the AB oscillations in the persistent currents carried by single-and few-particle states (see, e.g., Refs. [18][19][20][21][22][23][24]. Using an ultrasensitive torsion magnetometer, AB oscillations in the magnetic moment of In x Ga 1−x As self-assembled quantum rings have been observed 18 with a magnitude of oscillation as large as 60% to 70% of the corresponding magnitude in an ideal ring.…”

The two-level model of the excitonic Aharonov-Bohm effect in strained self-assembled semiconductor nanorings

“…In our recent work, we modeled excitons in 3D GaAs/(Al,Ga)As and (In,Ga)As/GaAs nanorings [5], and found that EAB oscillations can appear in the exciton ground energy level. Furthermore, strain in the (In,Ga)As/GaAs nanoring leads to a spatial separation of the electron and the hole like in a type-II quantum dot, which increases the exciton polarization.…”