Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 65: Transport Properties II (Theory)
HL 65.1: Vortrag
Mittwoch, 28. März 2012, 17:00–17:15, ER 164
Boltzmann equation approach to rectification at a potential step — •Stephan Rojek, Daniel Urban, Fred Hucht, and Jürgen König — Theoretische Physik, Universität Duisburg-Essen and CeNIDE, 47048 Duisburg, Germany
We study theoretically a two-dimensional electron gas with two regions separated by a potential step. A bias voltage parallel to the potential step leads to a transverse voltage proportional to the square of the applied bias voltage. This effect can be exploited for rectification, since the transverse voltage does not depend on the bias polarity. Our analysis is motivated by recent experiments [1, 2].
We model the system by means of the Boltzmann equation in the relaxation time approximation. We consider different relaxation times for scattering processes with energy transfer larger and lower than kBT based on inelastic and elastic scattering processes, respectively. In order to study the rectification effects, the distribution function has to be calculated to second order in the applied electric field. The contributions from the bulk to the transverse voltage promise to be relevant for the measured data. Direct effects of the potential step depend on the energy dependence of the relaxation times. The potential step leads to a finite charge accumulation on the length scale of the energy diffusion length. The transverse electric field of this non-uniform charge distribution can be the leading contribution to the transverse voltage. We discuss the relevance of our results for the measurements in Ref. [1, 2].
[1] A. Ganczarczyk et al., arXiv:0804.0689v3 (2009).
[2] A. Ganczarczyk et al., AIP Conf. Proc. 1199, 143 (2009).