The change in Si-AI bonding with metal coverage at the Si(111)^3 xV3^-AI interface

The self-consistent pseudopotential method is used to study the change in the bonding properties of the Si (111)>/3 X V3-A1 interface as a function of A1 coverage. For A1 coverages of ⅓,⅔, 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-AI 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 A1 atom favors the less coordinated on-top site over the threefold site. © 1988, American Vacuum Society. All rights reserved.