The change in Si–Al bonding with metal coverage at the Si(111)√3×√3–Al interface

The self‐consistent pseudopotential method is used to study the change in the bonding properties of the Si(111)(3)^1/2×(3)^1/2–Al interface as a function of Al coverage. For Al coverages of (1)/(3) , (2)/(3) , and 1 monolayer total energies, total charge densities and work functions are reported. We find, with the Al atom absorbed in a threefold site, that as the metal coverage increases the Si–Al chemisorption bond weakens, due to an outward relaxation of the Al overlayer, with a corresponding increase in the metallic character of the Al overlayer. We also find that at monolayer coverage the Al atom favors the less coordinated on‐top site over the threefold site.