Electronic and optical properties of acetylene and ethylene on Si(001)

In this work, we present the results of ab-initio theoretical calculations concerning the electronic and optical properties of Si(001) surface covered by small hydrocarbon molecules, namely acetylene and ethylene. As a result of the adsorption process, both molecules are covalently bonded to the surface, and we point out analogies and differences of the two systems under study. The most stable configurations have been taken into account at different coverages. We will show how band structure and reflectance anisotropy spectra calculations supply additional indirect information concerning the adsorption geometry and the saturation coverage, that have been longly debated.