The structural, electronic and transport properties of monatomic chains deposited onto silicon surfaces: A study at semi-empirical level

The purpose of this study is the assessment of the properties of deposited nanostructures with a perspective on the 1D limit. Therefore linear, single-atom chains deposited onto the Si(100) surface and onto monolayer steps of this surface have been considered. The elements forming the chains are covalent and metallic atoms, i.e. As, Al, Ni, Ag and Co, and the properties analyzed are the chain structure, its electronic charge and conductance. The calculations are based on a simple semi-empirical Hamiltonian, which is applied to the evaluation of both the electronic structure and the conductance, and on a cluster model of the exposed surface. The study of the structural properties shows that the linear structure is, in essence, maintained in all cases though some fuzziness is observed in the deposited structures. The binding energies and the density of states show a subtle, but appreciable, dependence on the structure of the exposed surface and on the chain composition. These differences are of paramount importance for the conductance and lead to the formation of well-defined resonances.