Berlin 2005 – scientific programme

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HL: Halbleiterphysik

HL 17: Poster Ib

HL 17.58: Poster

Friday, March 4, 2005, 16:30–19:00, Poster TU F

Spin dependent bleaching of the optical absorption in GaAs-QWs — •Michael Römer, Stefan Pfalz, Roland Winkler, Daniel Hägele, and Michael Oestreich — Universität Hannover, Institut für Festkörperphysik, Abteilung Nanostrukturen, Appelstraße 2, 30167 Hannover

The initial degree of spin polarization for optically excited electron-hole pairs in GaAs quantum wells is studied using time and polarization resolved photoluminescence spectroscopy. We observe a dramatic decrease of initial spin polarization with increasing excitation power. We argue that this decrease can be attributed to a spin dependent phase space filling. Optically created electrons and holes can partially block the creation of additional carriers, an effect known as bleaching of the optical resonance. This effect is spin dependent and effective as long as electrons and holes have not undergone a scattering event. A rate equation model yields good agreement with our experimental findings.