Evidence for a Dimer Reconstruction at a Metal/Silicon Interface.

We show that the stable structure of a CoSi sub 2 / Si (001) interface involves a 2x1 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 2x1 and 1x2 domains, ~100 nm in size, over many microns sup 2 of the interface.