Giant oscillations and increase of the photoluminescence efficiency of GaAs-AlGaAs modulation-doped multiquantum wells as a function of axial magnetic field

We investigate the effect of magnetic fields on the intensity of photoluminescence in GaAs-AIGaAs n-type modulation-doped multiple quantum well heterostructures. An overall increase in luminescence is observed with increasing axial field. Large oscillations in the intensity occur whose peaks and valleys are approximately periodic in 1/B. They cannot be correlated with Shubnikov-de Haas oscillations but possibly show an empirical relation with Landau level crossings of the lowest unoccupied subband states.