Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 37: Thermoelectric Materials (organized by DS)
TT 37.5: Vortrag
Dienstag, 17. März 2015, 10:30–10:45, H 0111
The Influence of a Distinct Diameter Variation on the Thermal Conductivity of Individual Bismuth Telluride Nanowires — •Danny Kojda1, Rüdiger Mitdank1, Anna Mogilatenko2, William Töllner3, Zhi Wang4, Michael Kröner4, Peter Woias4, Kornelius Nielsch3, and Saskia F. Fischer1 — 1AG Neue Materialien, Humboldt-Universität zu Berlin, D-10099 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
Calculations on indented nanowires (NWs) have shown that surface morphology can affect the thermal conductivity λ by phonon backscattering [1]. In order to determine the role of a distinct diameter variation, two Bi0.39Te0.61 NWs from the same batch are investigated by means of a combined full-thermoelectrical, structural and chemical characterization. Both NWs have the same chemical composition and the same direction of growth along the [110] direction. The NWs differ in their morphology. One NW shows a strong diameter variation between 190 nm and 320 nm and the other has a diameter of 187 nm with smooth sidewalls. At room temperature λ was determined by the 3ω-method and a reduction in the indented NW by about 50 % with respect to the smooth NW was observed. Hence, NW-vacuum interfaces perpendicularly arranged to the direction of transport can lead to a reduced λ in NWs [2]. [1] A. Moore et al., 2008 APL, 93 083112. [2] D. Kojda et al., 2014 Semicond. Sci. Technol., 29 124006.