Experimental molecular adsorption: electronic buffer effect of germanene on Al(1 1 1)
Résumé
The interaction of organic C 60 molecules with germanene grown on Al(1 1 1) is investigated by experimental tools and calculations. By mean of scanning tunneling microscopy, we show that a single but disordered C 60 layer is formed upon deposition in the monolayer range. Density functional theory calculations indicate that van der Waals and electrostatic interactions are present between the C 60 layer and the germanene, without formation of covalent bond. Moreover, the C 60 molecules are adsorbed without major crystallographic and charge modifications at the interface between germanene and the Al(1 1 1) substrate. The predicted charge transfer from the Al(1 1 1) substrate to the C 60 molecules is very small, which means that the germanene layer acts as an electronic buffer between the highly electron attractor C 60 molecules and the large electron reservoir Al(1 1 1). This leaves the C 60 layer quite uncharged, and so preserves its electron attractor properties for further layers grown on it, in the design of new molecular sensors.