title: Ultrafast dynamics of intersubband excitations in a quasi-two-dimensional hole gas.
abstract: We present the first study of ultrafast hole dynamics after resonant intersubband excitation in a quasi-two-dimensional semiconductor. p-type Si0.5Ge 0.5/Si multiple quantum wells are studied in pump-probe experiments with 150 fs midinfrared pulses. Intersubband scattering from the second heavy-hole back to the first heavy-hole subband occurs with a time constant of 250 fs, followed by intrasubband carrier heating within 1 ps. Such processes give rise to a strong reshaping of the intersubband absorption line, which is accounted for by calculations of the subband structure, optical spectra, and hole-phonon scattering rates.
authors.affiliation: Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2A, D-12489 Berlin, Germany.
authors.forename: R A
authors.initials: RA
authors.lastname: Kaindl
authors.forename: M
authors.initials: M
authors.lastname: Wurm
authors.forename: K
authors.initials: K
authors.lastname: Reimann
authors.forename: M
authors.initials: M
authors.lastname: Woerner
authors.forename: T
authors.initials: T
authors.lastname: Elsaesser
authors.forename: C
authors.initials: C
authors.lastname: Miesner
authors.forename: K
authors.initials: K
authors.lastname: Brunner
authors.forename: G
authors.initials: G
authors.lastname: Abstreiter