Dresden 2011 – scientific programme

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DS: Fachverband Dünne Schichten

DS 61: Thermoelectric Materials, Thin Films, and Nanostructures III (Focused Session -- Organisers: Nielsch, Rastelli, Balke)

DS 61.4: Talk

Friday, March 18, 2011, 16:45–17:00, GER 37

Thermoelectric power of nanostructured thin Au films — •Sebastian Schnurr, Ulf Wiedwald, and Paul Ziemann — Institut für Festkörperphysik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany

The effect of ordered arrays of nanostructures like nanopillars (periodicities 50 - 100 nm) on the Seebeck coefficient S of thin polycrystalline Au films (thickness t = 10-100 nm) is investigated as function of temperature in the range 6-300 K. Nanostructures are prepared by combining a micellar approach [1] with reactive ion etching. Reference measurements of S were performed on thin continuous films. At low temperature a phonon drag peak is found, which is significantly reduced as compared to bulk Au for thicker films while it completely vanishes for film thicknesses below 20 nm. At ambient temperature, S follows a [1−exp(−a· t)]-dependence similar to a recent report on thin Pt films [2].

For nanostructured Au films the ratio of the average grain size to the periodicity of nanostructures becomes important. For small grains (10-15 nm) electron scattering at grain boundaries dominates leading to a complete suppression of the influence of nanostructures. In the limit of large grains, however, scattering at nanostructures takes over decreasing S significantly below the reference level while its temperature dependence between 100 K and 300 K practically vanishes.

[1] U. Wiedwald et al., Beilstein J. Nanotechnol. 1, 24 (2010).

[2] M. C. Salvadori et al, Appl. Phys. Lett. 88, 133106 (2006).