title: Exploring two-dimensional electron gases with two-dimensional Fourier transform spectroscopy.
abstract: The dephasing of the Fermi edge singularity excitations in two modulation doped single quantum wells of 12 nm and 18 nm thickness and in-well carrier concentration of ∼4 × 10(11) cm(-2) was carefully measured using spectrally resolved four-wave mixing (FWM) and two-dimensional Fourier transform (2DFT) spectroscopy. Although the absorption at the Fermi edge is broad at this doping level, the spectrally resolved FWM shows narrow resonances. Two peaks are observed separated by the heavy hole/light hole energy splitting. Temperature dependent "rephasing" (S1) 2DFT spectra show a rapid linear increase of the homogeneous linewidth with temperature. The dephasing rate increases faster with temperature in the narrower 12 nm quantum well, likely due to an increased carrier-phonon scattering rate. The S1 2DFT spectra were measured using co-linear, cross-linear, and co-circular polarizations. Distinct 2DFT lineshapes were observed for co-linear and cross-linear polarizations, suggesting the existence of polarization dependent contributions. The "two-quantum coherence" (S3) 2DFT spectra for the 12 nm quantum well show a single peak for both co-linear and co-circular polarizations.
authors.affiliation: Department of Physics, University of South Florida, 4202 East Fowler Ave., Tampa, Florida 33620, USA.
authors.forename: J
authors.initials: J
authors.lastname: Paul
authors.affiliation: Department of Physics, University of South Florida, 4202 East Fowler Ave., Tampa, Florida 33620, USA.
authors.forename: P
authors.initials: P
authors.lastname: Dey
authors.affiliation: Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
authors.forename: T
authors.initials: T
authors.lastname: Tokumoto
authors.affiliation: CINT, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Reno
authors.affiliation: Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Hilton
authors.affiliation: Department of Physics, University of South Florida, 4202 East Fowler Ave., Tampa, Florida 33620, USA.
authors.forename: D
authors.initials: D
authors.lastname: Karaiskaj