Photoluminescence study of a dilute two-dimensional electron gas in GaAs-AlxGa1-xAs quantum wells

We report photoluminescence studies of GaAs-AlxGa1-xAs quantum wells doped with silicon donors in the GaAs layers. A series of samples with well widths between 80 and 375 was examined at T=70 K and in magnetic fields up to 8 T. The emission spectra contain simultaneously excitonic lines as well as features associated with interband transitions between conduction- and valence-band Landau levels. From our photoluminescence data, we determined the effective band gaps and the heavy-hole exciton binding energies of the quantum wells studied.