Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 13: Poster 1

HL 13.26: Poster

Montag, 26. März 2007, 15:00–17:30, Poster A

Spectrally resolved far-infrared photoresponse in quasi-Corbino quantum Hall systems — •Christian Notthoff and Axel Lorke — Festkörperphysik, Universität Duisburg-Essen, Lotharstraße 1, 47048 Duisburg

We present far-infrared (FIR) photoresponse measurements on different quasi-Corbino-shaped GaAs/AlGaAs heterostructures in the integer quantum Hall regime. We use a FT-FIR-Spectrometer as source and the sample it self as well as a Si-bolometer(for transmission measurements) as a detector. Contrary to the classical Hallbar-geometry, which exhibits their maximum sensitivity just below and above an integer filling factor [1,2], our samples show their max sensitivity at the integer filling factor. We find a sharp photoresponse-signal centred at the cyclotron-frequency with a nearly Lorenzian shape, which rapidly decreases in amplitude by varying the magnetic field away from an integer filling factor. Both observations show that the observed photoresponse is clearly not a bolometric effect but rather a direct result from resonat inter-Landau-level transition.

[1] J. Appl. Phys., Vol89, No 7 (April 2001) [2] PRB 63, 085320 (Oktober 2004)