Seminar of Dr. Bernd Gotsmann, October 21st

Endurance requirements in emerging probe technologies, such as probe-based data storage and lithography, are extremely demanding. Tip lifetime has been viewed as an unsolved critical issue in this context.
We show, that on the nanoscale the complexity of wear can be simplified to a thermally activated bond breaking process in which the energy barrier is reduced by the frictional shear stress. The resulting atom-by-atom wear deviates strongly from macroscopic wear behavior. Model predictions agree well with wear data obtained using sharp tips sliding in contact with various surfaces at sliding distances up to hundreds of meters. Wear data obtained using different tip materials is compared. Specifically, we used tips made from silicon, diamond-like carbon, and silicon carbide.
To obtain a deeper understanding of the atomistic arrangement in a nanoscale contact we use heat transfer between a tip and a surface to test atomistic models of true contact areas between contacting surfaces with atomic scale roughness. Our data is consistent with a ballistic thermal transport across individual atom-atom contacts distributed at the interface.