Atomic-scale friction on diamond(111) studied by ultra-high vacuum atomic force microscopy

The frictional properties of a diamond(111) single-crystal surface have been studied using an ultra-high vacuum atomic force microscope. while the presence or absence of hydrogen on the surface was monitored by low-energy electron diffraction (LEED). We have observed, for the first time, atomic-scale stick-slip features of a silicon tip on the hydrogen-terminated (1 x 1) diamond(111) surface. The distance between the stick-slip rows. measured perpendicularly to the rows, is typically 2-3 Angstrom, consistent with the lattice parameters of diamond. Removal of the hydrogen from the surface, indicated by a change in LEED pattern item (1 x 1) to (2 x 1), gives rise ro enormous stick-slip features at larger scale. The average friction coefficient on the hydrogen-free surface is found to be more than two orders of magnitude larger than on the hydrogen-terminated surface for loads rip to 30 nN. (C) 1997 Elsevier Science B.V.