Berlin 2015 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 26: Layer Properties: Electrical, Optical, and Mechanical Properties

DS 26.15: Vortrag

Mittwoch, 18. März 2015, 18:45–19:00, H 2032

Damping of metallized bilayer nanomechanical resonators at room temperature — •Maximilian Seitner, Katrin Gajo, and Eva Weig — Universität Konstanz, Fachbereich Physik, Konstanz, Germany

Nanoelectromechanical systems (NEMS) enable both the study of fundamental physical effects and future applications as integrated devices in ultra sensitive sensor technology. As an important representative, freely suspended nanomechanical string resonators are exploited for their remarkable mechanical properties, providing high quality factors even at room temperature. Hybrid nanostructures frequently rely on metallization films, providing functionalization for coupling mechanical resonators to other degrees of freedom. For those purposes, it is inevitable to acquire a deeper understanding of the metal's impact on the damping of the system as well as its influence on elastic parameters, especially at room temperature. We investigate the influence of gold thin-films subsequently deposited on a set of initially bare, doubly clamped, high-stress silicon nitride string resonators at room temperature. Providing analytical expressions for resonance frequency, quality factor and damping for both in- and out-of-plane flexural modes of the bilayer system we find the inverse quality factor to scale linearly with the gold film thickness, indicating that the overall damping is governed by losses in the metal. We extract mechanical quality factors of the gold film for both flexural modes and show that they can be enhanced by complete deposition of the metal in a single step, suggesting that surface and interface losses play a vital role in metal thin-films.