Regensburg 2013 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 24: Thermoelectric Materials

DS 24.5: Vortrag

Mittwoch, 13. März 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 T_B =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)