The effects of metallic contacts on silicon nanostructures studied quantum mechanically

The purpose of this study is to get insight into the effects of metallic contacts on nanocrystalline silicon material. Therefore the Hartree-Fock formulation at semiempirical level has been applied to silicon grains coated with an aluminum film. The calculations describe the electronic configuration of the grains and the effects induced by the presence of the metallic atoms. The parameters investigated are the binding and adsorption energies, the ionization potential and the Mulliken charges. Though no interdiffusion or lateral diffusion of metal atoms on silicon is observed, the electronic properties of grains appear perceptibly altered by the metallic overlayer and the strength of bonding is generally lowered in the structures with the contacts. Furthermore the built-in potential across the entire device exhibits a functional dependence on both the grain and the contact geometry which could be usefully applied for the fabrication of unconventional Schottky barriers devices.