Thermopower of a 2D Electron Gas in Suspended AlGaAs/GaAs Heterostructures

• Published in: Journal of electronic materials Vol. 41; no. 6; pp. 1286 - 1289
• Main Authors: Schmidt, M., Schneider, G., Heyn, Ch, Stemmann, A., Hansen, W.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.06.2012; Springer Nature B.V
• Subjects: Aluminum gallium arsenides; Characterization and Evaluation of Materials; Chemistry and Materials Science; Electric properties; Electron gas; Electronics and Microelectronics; Electrons; Gallium arsenide; Gallium arsenides; Heat conductivity; Instrumentation; Joining; Materials Science; Measurement; Membranes; Optical and Electronic Materials; Phonons; Solid State Physics; Two dimensional; Thermopower; thermal conductivity; HEMT; GaAs; suspended heterostructure
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-011-1826-3

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 with bulk material so that it is possible to establish a strong thermal gradient along the 2DEG even over a distance of a few micrometers. We find that the zero-field thermopower is significantly affected by the micropatterning. In contrast to 2DEGs incorporated in a bulk material, the diffusion contribution to the thermopower remains dominant up to temperature of 7 K, until the phonon drag becomes strong and governs 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 the piezoelectric coupling found for bulk phonons.