Role of the valence-band mass on the many-body optical properties of a two-dimensional electron gas

The Fermi-edge singularity and shake-up sidebands have been measured in the optical emission spectrum of a modulation doped single quantum well of InGaAs/InP with spatially variable Fermi energy and valence-band mass. Both magnitudes change across the sample due to a slight variation of the well width. The intensity of the optical Fermi-edge singularity at zero magnetic field increases with increasing hole mass, in excellent quantitative agreement with our many-body calculations, Emission spectra under a magnetic field at even filling factors show that, contrary to the Fermi-edge singularity, shake-up bands do not depend on the hole mass, in qualitative agreement with previous calculations. (C) 1998 Elsevier Science B.V. All rights reserved.