Relaxation of nonthermal hh and lh excitons in ZnSe quantum wells

H. Kalt, J. Hoffmann, M. Umlauff, Wolfgang Werner Langbein, Jørn Märcher Hvam

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    The strong exciton-LO phonon coupling in ZnSe QWs gives a direct access to the relaxation dynamics of nonthermal, free heavy-hole and light-hole excitons. Narrow hot-exciton distributions can be generated by LO-phonon assisted exciton formation. The thermalization of these excitons is monitored by cw or time-resolved phonon-sideband spectroscopy. A thermal exciton distribution evolves on a 100 ps timescale at low exciton densities when only scattering with acoustic phonons is possible. Exciton-exciton scattering accelerates the relaxation dynamics at high densities. Filling of the free heavy-hole exciton states and thermal population of the light-hole exciton states is observed. Measurements of the polarization degree after excitation with a sigma(+)-polarized picosecond pulse show that light-hole excitons with zero in-plane momentum change sign of their spin with each emission of an LO phonon.
    Original languageEnglish
    JournalIPPS physica status solidi (b)
    Volume206
    Issue number1
    Pages (from-to)103-109
    ISSN0370-1972
    DOIs
    Publication statusPublished - 1998

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