UNIVERSAL ASPECTS OF THE ATOMIC-SCALE FRICTION OF DIAMOND SURFACES

Several facets are observed when diamond films are produced by chemical vapor deposition methods. It is unknown, however, if all of these facets exhibit the same atomic-scale frictional behavior. In an effort to determine whether a facet or surface topological dependence of the atomic-scale friction of diamond exists, we have used molecular dynamics simulations to examine the friction which occurs when the (100)-(2 x 1) reconstructed surfaces of two diamond lattices are placed in sliding contact. Calculations are performed as a function of applied load, crystallographic sliding direction, and sliding velocity. Results from these calculations are compared with previous computations performed on a diamond (111) surface. We find that the general dependence of the friction coefficient, mu, on the applied load is similar, regardless of the facet. Indeed, this conclusion is supported by atomic force microscope experiments which have examined the friction of diamond (100) and (111) surfaces [Germann et al., J. Appl. Phys. 1993, 73, 163]. While the friction coefficients, and therefore the amount of energy dissipation, are similar regardless of facet, the atomic-scale motions which lead to energy dissipation differ slightly depending on the facet.