Regensburg 2010 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 13: Poster II: Electrical, mechanical and optical properties, nonlinear dielectrics

DF 13.2: Poster

Wednesday, March 24, 2010, 15:00–17:30, Poster A

Low frequency properties of space-charge wave excitation — •Thomas Schemme, Burkhard Hilling, Kay-Michael Voit, Heinz-Jürgen Schmidt, and Mirco Imlau — Department of Physics, University of Osnabrück, Germany

One possibility for the excitation of space-charge waves (SCW) in semi-insulating materials is the illumination with a superposition of one static and one moving interference pattern with equal spatial frequency and the application of a static electric field [1]. In this case, a constant ac signal at frequencies lower the resonance frequency of the SCW is uncovered. This low frequency signal does not persist using an oscillating pattern for excitation, i.e., it is a particular artefact of the four-beam excitation. To analyze this additional signal, both methods are analyzed comparatively in terms of their light pattern. We discuss the origin of the low frequency signal in the frame of a spatial modulation of the photoconductivity and give experimental evidence for our model approach. Thereby, a brief introduction into the theory describing the SCW-signal is presented. Financial support from the Deutsche Forschungsgemeinschaft within the Graduate College 695 is gratefully acknowledged.
[1] B. Hilling et al., PRB 80, 205118 (2009)