Step configurations near pinning sites on Ag(110)
Journal
Surface Science
Journal Volume
293
Journal Issue
3
Pages
183-194
Date Issued
1993
Author(s)
Abstract
Step configurations on Ag(110) near pinning sites have been measured under ultrahigh vacuum conditions with scanning tunneling microscopy (STM). At isolated pinning sites the surface structure is generally characterized by a high density of monatomic steps (step bunch) on the "lower" side of the pinning site and a very large (> 1000 Å) terrace on the "upper" side of the pinning site. The step bunch partially envelopes the pinning site, resulting in a curved interface between the step bunch and the upper terrace. We propose that the shape of the step bunches near these pinning sites reflects the local thermodynamic equilibrium between the surface tension of the curved step front and the pressure due to step-step interactions. These interactions are evaluated for steps with the same net orientation as the pinned steps via STM measurements of terrace width distributions. The distributions indicate that step-step interactions are predominantly entropie with a step stiffness of ~ kT/(5 Å). The Gibbs-Thomson relation, together with these measurements of step-step interactions, are used to predict the curvature of the step bunch-upper terrace interface at the pinning site. The predicted radius of curvature of 3000 Å for 50 Å mean step separation agrees with experimental observations. © 1993.
SDGs
Type
journal article