High resolution Si 2p photoelectron spectroscopy of unsaturated hydrocarbon molecules adsorbed on Si(100)c(4×2): the interface bonding and charge transfer between the molecule and the Si substrate

In order to elucidate the nature of the interface bonding between different molecules and a silicon surface, high resolution Si 2p photoelectron spectroscopy measurements were performed. After adsorption of unsaturated hydrocarbon molecules (ethylene, cyclopentene, and 1,4-cyclohexadiene), the peaks corresponding to the up and down atoms of surface asymmetric dimers vanished, while new peaks appeared between 215 and 398 meV relative to the bulk Si peak. These peaks are assigned to the di-σ Si–C bonds at the interface between the molecules and the surface. We can also estimate the amounts of reacted asymmetric dimers and the charge transfers from the peak intensities and the relative binding energies, respectively.