Fermi-Edge Singularity in Excitonic Spectra of Modulation Doped AlGaAs/GaAs Quantum Wells

M. Bugajskia, K. Regińskia, M. Godlewskib, M. Wesołowskia, P.O. Holtzc, A.V. Buyanovc and B. Monemarc aInstitute of Electron Technology, Al. Lotników 32/46, 02-668 Warsaw, Poland bInstitute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland cDepartment of Physics and Measurement Technology, Linköping University, 581 83 Linköping, Sweden

Full Text PDF

The dynamic response of an electron Fermi sea to the presence of optically generated holes gives rise to an enhanced interaction of correlated electron-hole pairs near the Fermi level, resulting in an enhanced oscillator strength for optical transitions, referred to as the Fermi-edge singularity. We studied this effect in modulation-doped quantum wells which provide confined dense Fermi sea, spatially separated from dopant atoms, easily accessible for investigations under low excitation conditions. The Fermi-edge singularity was observed in both photoluminescence and photoluminescence excitation experiments, although in the case of photoluminescence the samples had to be either co-doped with acceptors in the wells to provide necessary localization of holes or designed to allow for nearly resonant scattering between the electronic states near the Fermi energy and the next unoccupied subband of the 2D electron gas.

DOI: 10.12693/APhysPolA.90.751 PACS numbers: 71.35.+z, 85.30.De