FANO RESONANCES IN THE EXCITATION-SPECTRA OF SEMICONDUCTOR QUANTUM-WELLS

Fano resonances are observed in the photoluminescence excitation spect ra of GaAs-AlAs quantum wells. They originate from the Coulomb interac tion that couples a discrete state and a continuum of excitonic states belonging to different pairs of conduction and valence subbands. This interpretation is supported by our calculations and by the behavior o f the excitonic line shape in the presence of a magnetic field applied perpendicular to the layers.