This paper reports a molecular statics study of Cu surface diffusion barriers, particularly the facet–facet and step–facet barriers. The study focuses on two high-symmetry surfaces or facets, Cu{111} and Cu{100}. The results showed that these 2 barriers were distinct from conventional step barriers and were independent of facet size once it was beyond 3 atomic layers. Usually, the facet–facet barrier was substantially larger than diffusion barriers on flat surfaces or down monolayer steps, and the step–facet barrier was substantially larger than diffusion barriers along or across monolayer steps. Exceptions did exist. When two Cu{100} facets were involved, the two barriers decreased as the size of the ending facet increased from one layer to two layers, and then increase from two to three (or more) layers. As a result of the large facet–facet and step–facet barriers, surfaces of Cu thin films were of the order of 100 nm. The small facet–facet and step–facet barriers between two Cu{100} facets, when the ending facet was two to three layers, make it difficult to form another Cu{100} facet near one Cu{100} facet. For the same reason, nanowires along <100>/{100} on the Cu{100} were unlikely, while nanowires along <110>/{111} were feasible.

Diffusion Barriers on Cu Surfaces and Near Steps. J.Wang, H.Huang, T.S.Cale: Modelling and Simulation in Materials Science and Engineering, 2004, 12[6], 1209-25