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DS: Fachverband Dünne Schichten

DS 15: Thermoelectric Materials

DS 15.4: Vortrag

Dienstag, 8. März 2016, 10:30–10:45, H8

Surface Effects on Thermoelectric Properties of Single Crystalline Semiconducting Nanowires — •Danny Kojda¹, Rüdiger Mitdank¹, Anna Mogilatenko², William Töllner³, Zhi Wang⁴, Michael Kröner⁴, Peter Woias⁴, Kornelius Nielsch³, and Saskia F. Fischer¹ — ¹Novel Materials Group, Humboldt-Universität zu Berlin, D-12489 Berlin — ²Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, D-12489 Berlin — ³Institut für Angewandte Physik, Universität Hamburg, D-20355 Hamburg — ⁴Laboratory for Design of Microsystems, University of Freiburg - IMTEK, D-79110 Freiburg

Bismuth telluride nanowires (Bi₂Te₃ NWs) are proposed to reveal a thermoelectric figure of merit ZT that is influenced by confinement and surface effects. To determine the role of surface effects we consider individual single crystalline NWs as model system of a high surface-to-volume-ratio for which grain boundary scattering is negligible. We demonstrate the state-of-the-art of the combination of the structural, chemical, and temperature-dependent complete thermoelectric characterization for individual single crystalline Bi_0.39Te_0.61 NWs, which only differ in surface morphology. With the 3ω-method a reduction of the thermal conductivity of about 50 % is measured in a diameter varied NW with respect to a NW with a constant diameter [1]. For homogenous, diameter varied and single indented NWs finite element simulations are performed to interpret the measurement results [2].
D. Kojda et al., Semicond. Sci. Technol. 29, 124006 (2014).
D. Kojda et al., Phys. Status Solidi A, DOI:10.1002/pssa.201532464.