AVS 52nd International Symposium
    Surface Science Tuesday Sessions
       Session SS2-TuA

Paper SS2-TuA1
Temperature Dependence of Nanoscale Friction

Tuesday, November 1, 2005, 2:00 pm, Room 203

Session: Tribology, Adhesion and Friction
Presenter: A. Schirmeisen, University of Muenster, Germany
Authors: A. Schirmeisen, University of Muenster, Germany
L. Jansen, University of Muenster, Germany
H. Fuchs, University of Muenster, Germany
Correspondent: Click to Email
Friction processes at the nanoscale are the focus of numerous research projects, yet a comprehensive picture is still lacking. Despite the fact that most of the proposed models for energy dissipation in point contacts inherently depend on the sample temperature, this issue has been rarely addressed in experimental work. In this contribution we present nanoscale friction experiments with an ultrahigh vacuum atomic force microscope (AFM), where the sample temperature was varied by two orders of magnitude from 30 K to 300 K. Two different materials have been investigated: Graphite and silicon. On HOPG graphite atomic scale "stick-slip" is typically observed. Tribological properties of silicon contacts are of great interest in the area of MEMS/NEMS technology, where friction and wear are an important issue for the technical application of these devices. On graphite the overall friction increases monotonically when lowering the sample temperature. This behaviour can be understood in the framework of atomic scale "stick-slip" friction. The temperature influences the probability of the tip to jump between adjacent potential minima, in effect causing friction to decrease with increasing temperature.@footnote 1@ In contrast, the friction temperature curves on silicon show a rather complex behaviour, with a pronounced friction maximum at 100 K. Similar peaks have been found before in experiments, where internal friction properties of macroscopic vibrating silicon membranes were measured@footnote 2@ Those so-called "Debye-peaks" are related to thermally activated creation of defects in the bulk material, which leads to a strong enhancement of energy dissipation at the Debye temperature. We will discuss some of the intriguing similarities between our nanoscopic friction measurements and the concept of the Debye-peaks in bulk material. @FootnoteText@ @footnote 1@ Sang et al., Phys. Rev. Lett. 87 (2001) 174301@footnote 2@ Berry and Pritchet, J. Appl. Phys. 67 (1990) 3661.