Analysis of prefactors for interlayer diffusion of Ag/Ag(111)

Abstract

The parameters ${\ensuremath{\nu}}_{s}/{\ensuremath{\nu}}_{t}$ and $\ensuremath{\Delta}{E}_{s}$ for Ag/Ag(111) describing the interlayer diffusion probability $p=({\ensuremath{\nu}}_{s}/{\ensuremath{\nu}}_{t}{e}^{\ensuremath{-}(\ensuremath{\Delta}{E}_{s}/kT)})$ have been measured by different methods. Different results are obtained for the prefactor ratio ${\ensuremath{\nu}}_{s}/{\ensuremath{\nu}}_{t},$ with ${\ensuremath{\nu}}_{s}/{\ensuremath{\nu}}_{t}>1$ extracted at low temperatures $T<150\mathrm{K}$ while ${\ensuremath{\nu}}_{s}/{\ensuremath{\nu}}_{t}\ensuremath{\sim}1$ is extracted at higher temperatures $T=300\mathrm{K}.$ We examine as a possible reason for the discrepancy, the dependence of the step-edge barrier on the type of microscopic site (i.e., kinks vs straight-step sites) or whether long-range interactions play a role. Both factors can lead to non-Arrhenius temperature dependence. In addition we examine the conditions necessary for a steady state to hold in island decay experiments which are used to conclude ${\ensuremath{\nu}}_{s}/{\ensuremath{\nu}}_{t}\ensuremath{\sim}1$ and when such conditions are fulfilled for Ag/Ag(111).