Asperity contacts at the nanoscale: Comparison of Ru and Au

TitleAsperity contacts at the nanoscale: Comparison of Ru and Au
Publication TypeJournal Article
Year of Publication2008
AuthorsFortini A, Mendelev MI, Buldyrev S, Srolovitz D
Journal TitleJournal of Applied Physics
Date Published10/01
Type of ArticleArticle
ISBN Number0021-8979
Accession NumberISI:000260125500138
Keywords1/3(1123)(1011) DISLOCATIONS, adhesion, CLOSE-PACKED METALS, EMBEDDED-ATOM POTENTIALS, FORCE MICROSCOPE, HCP METALS, interatomic potentials, MEMS SWITCHES, molecular-dynamics, surfaces

We develop and validate an interatomic potential for ruthenium based on the embedded atom method framework with the Finnis/Sinclair representation. We confirm that the potential yields a stable hcp lattice with reasonable lattice and elastic constants and surface and stacking fault energies. We employ molecular dynamics simulations to bring two surfaces together, one flat and the other with a single asperity. We compare the process of asperity contact formation and breaking in Au and Ru, two materials currently in use in microelectromechanical system switches. While Au is very ductile at 150 and 300 K, Ru shows considerably less plasticity at 300 and 600 K (approximately the same homologous temperature). In Au, the asperity necks down to a single atom thick bridge at separation. While similar necking occurs in Ru at 600 K, it is much more limited than in Au. On the other hand, at 300 K, Ru breaks by a much more brittle process of fracture/decohesion with limited plastic deformation. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2991301]

Alternate JournalJ. Appl. Phys.