Stark and Zeeman effects in excitons in GaAs/GaAlAs quantum wells

Abstract

We have studied the effects of electric and magnetic fields in the excitonic spectrum of GaAs/GaAlAs quantum wells by means of low-temperature photoluminescence excitation spectroscopy. The electric field, perpendicular to the layers, couples different excited states of the heavy-hole exciton with the ground state of the light-hole exciton. As a result of this coupling, fine structure becomes visible in the spectra. A small magnetic field (∼0.5 Tesla) is applied to remove degeneracies of the excitons and to enhance the oscillator strength of excited exciton-states. These states are resolved with the use of circularly polarized light, which enables us to separate the Zeeman components of the excitons. We are able to assign all the peaks appearing in the complicated excitonic fine structure by comparison with calculations, which take into account valence-band mixing and electric and magnetic field effects. © 1989.