Evidence for a dimer reconstruction at a metal-silicon interface

We show that the stable structure of a ${\mathrm{CoSi}}_2$/Si(001) interface involves a 2×1 periodic array of Si dimers with bond length 0.23±0.02 nm. We use a novel combination of quantitative transmission-electron diffraction, transmission-electron-microscope (TEM) imaging, and high-resolution TEM to solve the structure and have imaged separate 2×1 and 1×2 domains, ∼100 nm in size, over many μ${\mathrm{m}}^2$ of the interface.