Regensburg 2004 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 12: Poster I

HL 12.47: Poster

Montag, 8. März 2004, 16:30–19:00, Poster A

Spectroscopic and transport measurements in the quantum Hall regime on an optimized structure — •Claas Bierwisch¹, Stefanie Döhrmann¹, Daniel Hägele¹, Peter Tranitz², Werner Wegscheider², and Michael Oestreich¹ — ¹Universität Hannover, Institut für Festkörperphysik, Abteilung Nanostrukturen, Appelstr. 2, D-30167 Hannover — ²Universität Regensburg, Institut für Angewandte und Experimentelle Physik, D-93040 Regensburg

We combine optical and transport measurements on a two-dimensional electron gas (2DEG) in the quantum Hall regime on a sample with optimized properties for optical investigations. The sample is a MBE grown modulation doped 20 nm GaAs/Al_xGa_1−xAs single quantum well structure with an electron density of about 10¹¹ cm⁻² and a high mobility of ∼ 10⁶ cm²V⁻¹s⁻¹. A high reflectance AlGaAs/AlAs Bragg mirror below the 2DEG together with the reflecting top layer of the sample constitute a cavity around the optical active quantum well. Simulations of the expected optical Faraday-signal in reflection geometry exhibit a signal enhancement of almost one order of magnitude due to the presence of the mirror. Using a Hall bar, we observe the integer quantum-Hall-effect and Shubnikov-de Haas-oscillations in a magnetic field up to 8 T at a temperature of 1.8 K. Time-resolved photoluminescence (PL) experiments using a streak camera system yield electron and hole spin dynamics inside the quantum well. Simultaneous PL and transport measurements at different filling factors will be presented.