New ballistically and thermally activated exchange processes in the vapor deposition of Au on Ag(111): a molecular dynamics study

Diffusion processes of Au on Ag(111) are examined by molecular dynamics calculations using surface-embedded-atom potentials. Mie find that complex forms of exchange diffusion dominate the early deposition. The usual direct Au-Ag exchange is unlikely, but more complicated exchange mechanisms involving multiple substrate atoms and catalyzed by nearby adatoms or clusters have very low activation barriers. These highly collective exchange processes can be activated ballistically by an incoming adatom or thermally on surfaces well below room temperature. (C) 1998 Elsevier Science B.V. All rights reserved.