Dresden 2011 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 44: Functional Materials II

MM 44.4: Talk

Friday, March 18, 2011, 11:15–11:30, IFW A

Combined impact of microstructure and mechanical stress on PdHc thin films electrical resistivity — •Stefan Wagner and Astrid Pundt — Institut für Materialphysik, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

Physical properties of metal thin films strongly depend on their microstructure and stress state. [1] Palladium hydrogen (PdHc) thin films are used as a model system to determine the impact of microstructure and mechanical stress release on the electrical resistivity of thin film metals and alloys that undergo structural phase transitions. The results are compared with bulk resistivity models. Nanocrystalline, multi-oriented and epitaxial films in the thickness range from 5 nm to 2 μm are investigated, yielding initial terminal resistivities of 152 - 200 Ωnm. The hydrogen-related resistivity changes of epitaxial films are shown to approach the predicted α-phase bulk increment Δρ/ΔcH = 451 Ωnm, while hydrogen trapping in nanocrystalline films strongly reduces the resistivity response. In the two phase field the resistivity is shown to be modified by the sterical distribution and geometry of the hydride precipitates, yielding different proportions of serial and parallel conduction. Film delamination from the substrate strongly reduces the resistivity increment due to the Gorsky effect. [2,3]

[1] Wagner S, Pundt A: APL 2008;92:051914. [2] Wagner S, Pundt A: Acta Mat 2010;58:1387. [3] Wagner S, Pundt A: Acta Mat, accepted.