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Fermi-edge singularity and screening effects in the absorption and luminescence spectrum of Si delta-doped GaAs.

Fermi-Kanten-Singularität und Abschirmungseffekte im Absorptions- und Lumineszenzspektrum von Si delta-dotiertem GaAs
: Fischer, A.; Ploog, K.; Wagner, J.


Applied Physics Letters 59 (1991), Nr.4, S.428-430 : Abb.,Lit.
ISSN: 0003-6951
ISSN: 1077-3118
Fraunhofer IAF ()
delta-doping; Delta-Dotierung; Fermi edge singularity; Fermi-Kanten-Singularität; GaAs

We have investigated single Si delta-doped layers in GaAs by photoluminescence and photoluminescence excitation spectroscopy (PLE). When the photogenerated holes are confined by GaAs/Al sub x Ga sub 1-x As heterointerfaces placed at either side of the doped layer strong radiative recombination is observed from the quasi-two-dimensional electron gas associated with the delta-doping spike. The low-temperature absorption spectrum involving spatially direct transitions, which was measured by PLE, shows a well resolved enhancement at the Fermi edge. The energy position of the absorption edge is found to be independent of the excitation intensity. The peak energy of the band-to-band emission spectrum, in contrast, which involves spatially indirect transitions, shows a shift to higher energies with increasing excitation intensity due to the screening of the space-charge-induced potential by photogenerated carriers.