HIGH EXCITON BINDING-ENERGIES IN GAAS/GAAIAS QUANTUM-WELLS

Binding energies of excitons in GaAs-Ga1-xAlxAs quantum wells are calculated including valence band mixing and also Coulomb coupling between excitons belonging to different subbands, nonparabolicity of the bulk conduction band, and the dielectric mismatch between well and barrier materials. All these effects are of a comparable importance, tend to increase the binding energy, and taken together result in very high binding energies, particularly in narrow GaAs/AlAs quantum wells. A comparison with photoluminescence excitation (PLE) and magneto-optical (MO) experiments shows better agreement with the PLE results, and suggests that binding energies deduced from MO experiments have a larger intrinsic error. © 1991.