Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 78: Nanostructures at Surfaces IV: Various Aspects

O 78.4: Talk

Thursday, March 10, 2016, 11:15–11:30, S052

Modeling AFM Adhesion Measurements on Rough Substrates — •Till Junge, Michael Schäfer, Christian Greiner, and Lars Pastewka — IAM-CMS, KIT, Karlsruhe, Germany

Understanding adhesion forces in dry contact is of particular importance for the study of both technical and biological micro- and nanoelectromechanical systems. Even in their simplest manifestation -- the pull-off force necessary to break the contact between a nano-scale indenter and a rough surface -- they are poorly understood. We here use a boundary element method in combination with an empirical interaction potential the contact of a stiff spherical indenter of varying size acting on an elastic rough substrate. The model is compared to a series of atomic-force microscopy (AFM) pull-off measurements performed with silicon tips with tip radii varying between 14 nm and 100 nm on an ultrananocrystalline diamond (UNCD) substrates. Without any fitting parameters, we find good agreement between the experiment and our simulations. We use our simulations to analyze the link between distribution of pull-off forces and statistics of surface roughness of the substrate. This enables in particular extraction of small scale features of the rough topography not accessible by standard AFM measurements, such as the root mean square slope of surface roughness.