Electron energy loss spectroscopy of the Si(111)—simple-metal interface

New data are presented on the formation of Schottky barriers on Si(111) 7 ×{} 7 with evaporated Al, Ga, or In metal. Electron-energy-loss spectra (ELS) have been taken as a function of metal overlayer coverage. The removal of clean surface state transitions has been observed at submonolayer coverage. The behavior of interface collective excitations of bulk-silicon-like transitions and of transitions from the metal core levels confirm the covalent character of the interface chemical bonds.