Regensburg 2013 – scientific programme
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DS: Fachverband Dünne Schichten
DS 24: Thermoelectric Materials
DS 24.5: Talk
Wednesday, March 13, 2013, 15:45–16:00, H32
Thermoelctrical Measurements on Single Bi2Te3 Nanowires — •Danny Kojda1, Rüdiger Mitdank1, Zhi Wang2, Michael Kröner2, Peter Woias2, William Töllner3, Kornelius Nielsch3, and Saskia F. Fischer1 — 1Novel Materials, Humboldt-Universität zu Berlin, D-10099 Berlin — 2IMTEK, University of Freiburg, D-79110 Freiburg — 3University of Hamburg, D-20355 Hamburg
Nanowires (NWs) made of Bi2Te3 are expected to improve the thermoelectric efficiency. In order to investigate the thermoelectric properties (Seebeck coefficient, electrical and thermal conductivity), as well as the crystal structure via TEM for one and the same NW, a special measurement device was fabricated by means of silicon micromachining [1]. This device contains two symmetric Si cantilevers (with a 4 µm gap) where the NW is deposited in between via dielectrophoresis and contacted in four point geometry via electron beam assisted deposition of Pt. Thin Pt micro-heaters and Pt-thermometers are situated near the NW to create and measure a temperature gradient. In the bath temperature range TB =4.2 K-300 K we measured the temperature dependent resistance of a single Bi2Te3-NW, observing metallic behavior. We also measured the Seebeck voltage between the NW-endings and a resistance change of the heated thermometer lead as function of the heating current and bath temperature. With this we are able to calculate tempeature dependent the Seebeck coefficient. It has an absolute maximum of −35 µ V/K at about 200 K.
Z. Wang et al., Sens. and Actuat. A: Phys. (188; p. 417-426; 2012)