The diffusion of adsorbed Si dimers on the Si(001)-2 × 1 surface is studied with hot scanning tunneling microscopy and a tracking technique in which each diffusive event is resolved. The activation energy for diffusion of a dimer along the top of a substrate dimer row is found to be 1.09 ± 0.05 eV, with an attempt frequency of 1013.2±0.6 Hz. A lower bound of 1.40 eV is placed on the activation energy for dimer dissociation. The free energy of a dimer is observed to decrease by 32 ± 2 meV at a site adjacent to a type-A step.
Bibliographical noteFunding Information:
We are grateful to C.J. Palmstrom for suggesting the melting point of In as a temperature calibration. We thank K. Terakura for permission to reprint figures from Ref.  and for his useful correspondence, and we thank J. van Wingerden and B.S. Swartzentruber for preprints of their work. Hot STM movies of dimer diffusion can be viewed at our World Wide Web site, http://www.spa.umn.edu/groups/stmlab/. This research was supported by National Science Foundation Grants DMR-9222493 and DMR-9614125.
Copyright 2017 Elsevier B.V., All rights reserved.
- Epitaxy growth
- Models of surface kinetics
- Molecular dynamics
- Scanning tunneling microscopy
- Stepped single crystal surfaces
- Surface diffusion