Published online by Cambridge University Press: 21 February 2011
A general concept is shown how to measure both the barriers for terrace and step-down diffusion for an epitaxial system. It is based on the application of mean-field nucleation theory to variable temperature STM data. With this approach we studied the influence of strain on intra- and interlayer diffusion for Ag self diffusion on strained and unstrained Ag(111) surfaces. The strained surface was the first Ag layer that grows pseudomorphically on Pt(111) and is thus under 4.2% compressive strain. The barrier for terrace diffusion is observed to be substantially lower on the strained, compared to the unstrained Ag/Ag(111) case, 60±10 meV and 97±10 meV, respectively. The additional barrier for interlayer diffusion decreases from 120±15 meV for Ag(111) homoepitaxy to only 30±5 meV for diffusion from the strained Ag layer down to the Pt(111) substrate. These examples illustrate the considerable effect of strain on the intra- and interlayer mass transport. They require a new concept of layer dependent nucleation kinetics for heteroepitaxial systems in general.