Localization of negatively charged excitons in GaAs/AlGaAs quantum wells

The localization of negatively charged excitons on isolated charged donors, located in a barrier at various fixed distances L from the heteroboundary, is investigated in isolated GaAs/AlGaAs quantum wells. The energy shift of the cyclotron replica in the emission spectra of a localized excitonic complex is studied as a function of L. It is shown that in undoped samples charged excitons localize on residual donors at distances L>350 Å on account of the formation of D ^? complexes at shorter distances. It is established that a cyclotron replica arises with the recombination of an excited state and not the ground state, as previously thought, of an excitonic complex.