Observation of the Fermi edge anomaly in the absorption and luminescence spectra of n-type modulation-doped GaAs-AlGaAs quantum wells

A well defined sharp peak was observed in the absorption and luminescence spectra near the absorption edge of n-type modulation-doped GaAs-Al x Ga 1-x As multiple quantum wells. The peak is assigned as the Fermi edge anomaly similar to the many-body effects in the soft X-ray spectra of metals. As the temperature was raised above 10 K, the peak disappeared, but it was restored by the application of magnetic field. The magnetic field dependence of the peak indicates that it has an excitonic character.