Terahertz photoresponse of a quantum Hall edge-channel diode

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2009

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The terahertz (THz) photoresponse of a two-dimensional electron gas in the quantum Hall regime is investigated. We use a sample structure which is topologically equivalent to a Corbino geometry combined with a cross-gate technique. This quasi-Corbino geometry allows us to directly investigate the THz-induced transport between adjacent edge states, thus avoiding bulk effects. We find a pronounced photovoltage at zero applied bias, which rapidly decreases when an external current bias is applied. The photovoltage 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 at the sample edge. Using the sample as a detector in a Fourier-transform spectrometer setup, we find a resonant response from which we extract a reduced effective cyclotron mass. The findings support a nonbolometric mechanism of the induced photovoltage and the proposed edge-channel diode model. © 2009 The American Physical Society.

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Forschungsinformationssystem der UHH

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