Metal−Molecule Interfaces Formed by Noble-Metal−Chalcogen Bonds for Nanoscale Molecular Devices

Using benzenethiol and benzeneselenol monolayers on Ag(111) and Cu(111) substrates, we systematically studied the electronic states of metal−molecule interfaces formed by noble-metal−chalcogen bonds. X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy revealed that the Ag−S, Ag−Se, and Cu−S interfaces retain their metallic nature, whereas the Cu−Se interface gets oxidized. On the basis of the results of this study and our previous study, we conclude that, among Au−S, Au−Se, Au−Te, Ag−S, Ag−Se, Cu−S, and Cu−Se interfaces, Au−Se is most suitable for nanoscale molecular devices. We found a screening parameter of 0.5 in the metal−molecule interface system, indicating that interfacial electronic states near the Fermi level are produced at the interface between the noble metal and molecule. However, we expect the density of states that originates from molecules near the Fermi level to be very small. The findings imply that the electrical conduction mechanism of metal−single-molecule−meta...