Interaction of magnetoexcitons and two-dimensional electron gas in the quantum Hall regime

We have investigated the influence of a two-dimensional electron gas on interband optical transitions in an (In,GaAs) modulation doped single quantum well under conditions where the Fermi level is very near the n=2 conduction subband and a many-body exciton is observed from this subband. Strong variations occur in external magnetic fields in both the exciton spectrum and its amplitude of which the latter correlates with the longitudinal Hall resistance in the quantum Hall regime.