MAGNETOPLASMON REPLICA IN THE RECOMBINATION RADIATION SPECTRA OF A QUASI-2-DIMENSIONAL ELECTRON-GAS IN GAAS ALGAAS QUANTUM-WELLS/

The radiative recombination spectra of two-dimensional electrons with free photoexcited holes are investigated for a wide variety of GaAs/Al GaAs quantum wells, with different thicknesses and electron densities. It is found that for certain, close to integral, filling factors an i ntense line corresponding to an Auger process - radiative recombinatio n with the emission of an additional magnetoplasmon - appears in the l uminescence spectrum. The new line is shifted to lower energies with r espect to the zero Landau level, and the magnetic field dependence of the energy splitting between these lines agrees with the theoretical c oncepts of the dispersion of magnetoplasmon excitations. This makes it possible to estimate the magnetoplasmon energy at the roton minimum. (C) 1997 American Institute of Physics.