Hamburg 2001 – scientific programme

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HL: Halbleiterphysik

HL 24: Poster II

HL 24.34: Poster

Thursday, March 29, 2001, 10:30–19:00, Rang S\ 3

Temperature Dependence of the Homogeneous Linewidth of Localized Excitons in GaAs/AlAs Superlattices — •H. Zhao, S. Wachter, and H. Kalt — Institut für Angewandte Physik, Universität Karlsruhe , D-76128 Karlsruhe

We report investigations on the temperature dependence of the homogeneous linewidth of localized excitons in GaAs/AlAs type-II superlattices. The sample contains 140 periods of GaAs(3nm)/AlAs(2.8nm). The luminescent intensity map shows bright spots related to type-I localized centers. We measured the spectra from bright spots at different temperatures by micro-photoluminescence with 1µm spatial resolution and 30µeV spectral resolution. Sharp lines of lorantzian shape were found in these spectra, and the linewidth increases with temperature. By fitting the temperature dependence of the linewidth, we deduced the constants describing exciton-acoustic phonon and exciton-LO phonon interactions, and the low-temperature limitation of the linewidth. We compared the results with that of free excitons in GaAs 2D systems as well as 0D systems, to show the influence of confinement on exciton-phonon interactions.