title: Interacting drift-diffusion theory for photoexcited electron-hole gratings in semiconductor quantum wells.
abstract: Phase-resolved transient grating spectroscopy in semiconductor quantum wells has been shown to be a powerful technique for measuring the electron-hole drag resistivity ρ(eh), which depends on the Coulomb interaction between the carriers. In this Letter we develop the interacting drift-diffusion theory, from which ρ(eh) can be determined, given the measured mobility of an electron-hole grating. From this theory we predict a crossover from a high-excitation-density regime, in which the mobility has the "normal" positive value, to a low-density regime, in which Coulomb drag dominates and the mobility becomes negative. At the crossover point, the mobility of the grating vanishes.
authors.affiliation: Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA.
authors.forename: Ka
authors.initials: K
authors.lastname: Shen
authors.forename: G
authors.initials: G
authors.lastname: Vignale