AFM investigation of tribological properties of nano-patterned silicon surface

The tribological properties of a nano-patterned Si surface have been investigated in ambient condition by atomic force microscopy (AFM). Thepattern, consisting of parallel grooves, was realized on a Si(0 0 1) single crystal via focused ion beam (FIB) milling. The same technique was usedto modify a commercial Si probe in order to obtain a flat tip, suitable for the tribological characterization of the patterned surface, since it presentsan extended contact area. The dependence of the lateral force on the normal load has been studied, varying the sliding speed and the fast scandirection with respect to the pattern orientation. Lateral force versus normal load curves show a linear trend except in the region closed to thepull-off limit. In this region adhesive effects related to ambient condition strongly affect the process. This behavior is more evident on the pristinesurface. Experimental results show that the friction coefficient is sensibly lower on the patterned area than on the unpatterned one. A non-negligiblewear of the patterns related to the sliding of the flat tip has been detected.© 2007 Elsevier B.V. All rights reserved.