ROLE OF THE VALENCE-BAND MASS ON THE MANY-BODY OPTICAL-PROPERTIES OF A 2-DIMENSIONAL ELECTRON-GAS

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