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.
- Epitaxy growth
- Models of surface kinetics
- Molecular dynamics
- Scanning tunneling microscopy
- Stepped single crystal surfaces
- Surface diffusion