Magneto-oscillations in the electroluminescence intensity of resonantly coupled GaAs-AlAs superlattices: The magnetoexciton resonance

The dependence of the electroluminescence (EL) signal from excited-state interband transitions on the applied magnetic field has been investigated for two superlattice samples. Both samples show clear oscillatory behavior of the EL intensity as a function of the perpendicular magnetic field. In the sample with a subband splitting of the lowest conduction band states above the longitudinal-optical (LO) phonon energy in GaAs, the oscillations are due to the magnetophonon effect. However, in the sample with a subband splitting below the LO-phonon energy of GaAs, two series of oscillations exist, which are assigned to a different relaxation mechanism. the magnetoexciton resonance. The intersubband scattering process is enhanced at certain magnetic-field strengths due to the scattering of free carriers by excitons.