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DS: Fachverband Dünne Schichten
DS 15: Thermoelectric Materials
DS 15.3: Talk
Tuesday, March 8, 2016, 10:15–10:30, H8
Full thermoelectric characterization of individual silver-nanowires — •Rüdiger Mitdank1, Danny Kojda1, Zhi Wang2, Johannes Ruhhammer2, Michael Kroener2, Peter Woias2, Martin Albrecht3, and Saskia F. Fischer1 — 1Novel Materials Group, Institut für Physik der Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany — 2Laboratory for Design of Microsystems, University of Freiburg - IMTEK, 79110 Freiburg, Germany — 3Leibniz-Institut für Kristallzüchtung, Max-Born-Str. 2 , 12489 Berlin, Germany
A full characterization of the thermoelectric properties of nanowires (NWs) requires information about the Seebeck coefficient as well as the electrical and thermal conductivity. The temperature normalized ratio of both conductivities is known as Lorenz number L and is discussed for Ag-NWs in [1]. In order to determine the thermoelectric figure of merit of Ag-NWs, individual Ag-NWs are transferred to a micro machined measurement platform (TNCP) and contacted by electron beam induced deposition (EBID) with platinum. The focus of this talk is directed to the discussion of the temperature-dependent Seebeck coefficient of Ag-NW's. The thermovoltage of Ag-NWs was measured with respect to Pt between 4 K and 300 K. The Seebeck coefficient S changes the sign at T = 150 K and exhibits a minimum at T = 70 K. This zero-crossing and the influence of the phonon drag are discussed. As a result, the figure of merit S*S/L is discussed for the temperature-range between 4 K and 300 K.
[1] D. Kojda et. al. Phys. Rev. B, 91, 024302 (2015)