FERMI EDGE SINGULARITY IN THE LUMINESCENCE OF MODULATION-DOPED GA0.47IN0.53AS/AL0.48IN0.52AS SINGLE HETEROJUNCTIONS

Modulation-doped Ga0.47In0.53As/Al 0.48In0.52As single heterojunctions have been investigated by means of optical spectroscopy and magnetotransport measurements. Strong radiative recombination of the two-dimensional electron gas (2DEG) with photogenerated holes has been observed. The recombination is not k conserving, since the holes are weakly localized at the heterointerface opposite to the 2DEG region. At low temperature strong Fermi edge enhancement occurs in the luminescence of single heterojunctions with, for example, a dense electron sheet concentration of 2.5×1012 cm- 2. The results show clear evidence for the influence of carrier concentration and temperature on the Fermi edge singularity. The linewidths of the luminescence spectra agree well with those estimated from the electron sheet carrier concentrations, which were determined from the Shubnikov-de Haas oscillations, using an ideal 2DEG model.