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arXiv · 1111.1303

Thermopower of a 2D electron gas in suspended AlGaAs/GaAs heterostructures

M. Schmidt·G. Schneider·Ch. Heyn·A. Stemmann·W. Hansen
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Abstract

We present thermopower measurements on a high electron mobility two-dimensional electron gas (2DEG) in a thin suspended membrane.We show that the small dimension of the membrane substantially reduces the thermal conductivity compared to bulk material so that it is possible to establish a strong thermal gradient along the 2DEG even at a distance of few micrometers. We find that the zero-field thermopower is significantly affected by the micro patterning. In contrast to 2DEGs incorporated in a bulk material, the diffusion contribution to the thermopower stays dominant up to a temperature of 7 K until the phonon-drag becomes strong and governs the run of the thermopower. We also find that the coupling between electrons and phonons in the phonon-drag regime is due to screened deformation potentials, in contrast to piezoelectric coupling found with bulk phonons.

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M. Schmidt, G. Schneider, Ch. Heyn, A. Stemmann, W. Hansen. 2011-11-05. Thermopower of a 2D electron gas in suspended AlGaAs/GaAs heterostructures. https://doi.org/10.1007/s11664-011-1826-3

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