Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 18: Quantum Hall Effect
HL 18.2: Talk
Monday, March 14, 2011, 14:45–15:00, POT 151
THz photoresponse of quantum Hall edge channels — •Christian Notthoff1,2, Kevin Rachor3, Detlfe Heitmann3, Dirk Reuter4, Andreas Wieck4, and Axel Lorke2 — 1Nanoparticle Process Technology, Universität Duisburg-Essen, Lotharstr.1, D-47048 Duisburg — 2Fachbereich Physik, Universität Duisburg-Essen, Lotharstr.1, D-47048 Duisburg — 3Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11,D-20355 Hamburg — 4Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum
We present THz photoresponse measurements on quasi-Corbino-shaped GaAs/AlGaAs heterostructures in the quantum Hall regime. A Fourier spectrometer is used as a broad band, black-body source with a very low spectral intensity compared to THz-Lasers used in other experiments. At filling factors ν > 2, we find two independent contributions to the photoresponse-signal. One contribution clearly results from bolometric heating inside the bulk and the other one is caused by a non-bolometric mechanism. Furthermore, combining the quasi-Corbino shape with a cross-gate technique allows us to directly investigate the THz-induced transport between adjacent edge states, thus avoiding bulk effects. In the absence of bulk effects a pronounced photo voltage at zero applied bias is revealed. The photo voltage and its dependence on the bias current can be described using the model of an illuminated photodiode, resulting from the reconstruction of the Landau bands of the sample edge. Moreover, the photodiode model is also applicable to the samples where the bulk effects are present.