* Corresponding author. Fax: #(33) 4 76 85 56 10; e-mail: potemski@labs.polycnrs-gre.fr. Physica B 249—251 (1998) 566—570 Emission from a two-dimensional electron gas in quantizing magnetic fields M. Potemski*, L. Gravier, A. Tru¨by, D.K. Maude, P. Hawrylak, Zb. Wasilewski, B. Etienne  Grenoble High Magnetic Field Laboratory, MPI/FKF and CNRS, 25 Avenue des Martyrs, BP 166, 38042 Grenoble Cedex 9, France  Institute for Microstructural Sciences, NRC, Ottawa, Canada K1A OR6  Laboratoire des Microstructures et de Microelectronique, CNRS, 92 220, Bagneux, France Abstract Luminescence spectra of two-dimensional electron gases measured in magnetic fields up to 32 T and temperature range between 150 mK and 10 K are reported. Systems with appreciable disorder exhibit magneto-oscillations in the total intensity and the line-width. These oscillations are interpreted in terms of a magnetic-field modulation of the screening efficiency. Recombination spectra of high-mobility electron gases show unusual features around integer filling factors . The observed red-shifts of the luminescence line at "1, 2 are attributed to the discontinuous transition across the filling factor from a recombination dominated by an excitonic effect to a recombination dominated by the much stronger electron—electron interaction effects. A doublet-like emission observed at "3, 5 is assigned to final state interactions involving spin wave excitations and can be viewed as the Anderson—Fano resonance in the Fock space.  1998 Elsevier Science B.V. All rights reserved. Keywords: Quantum Hall effect; Correlated electrons; Photoluminescence Magneto-luminescence spectra of two-dimen- sional electron gases (2DEG) are known to show the non-monotonic field dependences of energy positions and/or intensities of the observed emis- sion peaks. These deviations from a simple, one- particle Landau level geometry are often assigned to many body interactions. One may distinguish two kinds of effects related to carrier—carrier inter- action and studied in magneto-luminescence of a 2DEG. One type of effects are those already present in the absence of magnetic fields but con- siderably modulated under conditions of Landau quantization as a result of the appreciable modifi- cation of the density of states. Phenomena such as, e.g., magnetic field modulation of the band gap renormalization, shake up replicas, inter landau level Auger recombination, belong to this first group and have been widely studied in the regime of the Integer Quantum Hall Effect (IQHE) in case of structures with appreciable disorder [1]. On the 0921-4526/98/$19.00  1998 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 5 2 6 ( 9 8 ) 0 0 1 8 7 - 2