Organic Molecule Adsorption on Stepped Si-Au Surfaces: Role of Functional Group on Geometry and Electronic Structure

Stepped gold-stabilized Si(111) surfaces offer much potential for self-organized assembly of one- and two-dimensional nanostructured arrays of organic molecules due to the presence of regular atomic chains of Au and Si on the surface, parallel to the step edges. In this theoretical study, the adsorption of various simple organic molecules with different functional groups on the Si(553)-Au surface has been investigated. It has been found that adsorption at the step edge site is favored by all species. If the step edge is first passivated by hydrogen, adsorption occurs on Si atoms on the terraces. Instead, adsorption on the gold chains is completely unfavored. The influence of organic molecule adsorption on the electronic band structure and surface metallicity is investigated.