Longitudinal-optical phonon and shake-up excitations in the recombination spectra of semiconductor quantum wells

The observation of both LO-phonon and inter-Landau-level magnetoplasmon shake-up excitations in the magnetophotoluminescence spectra of quantum wells containing high densities of free carriers is reported. The inter-Landau-level magnetoplasmon excitations occur at energies greater than the bare Landau-level separations, in agreement with the predictions of many-body theory. Clear evidence for LO-phonon–magnetoplasmon coupled-mode behavior is observed.