INTERFACIAL CHARACTERIZATION OF ION-BEAM-DEPOSITED AC FILMS ON GE

Diamondlike carbon films were deposited on germanium crystals with a m ass-separated C+ ion beam in ultrahigh vacuum over the energy range 20 -275 eV, and the interfaces were characterized with x-ray photoelectro n spectroscopy. It was found that ion bombardment induced a carbide ph ase on the germanium surface. Further carbon accumulation then led to the growth of an amorphous carbon overlayer. The carbide phase was ide ntified by a rather low C 1s binding energy (at about 283.8 eV) and sm all positive shift of the Ge 3p peak (about 0.4 eV). The valence-band spectra of these samples also suggested that germanium carbide formed with a pure carbon beam for the bombardment energy range considered ha s a band gap between germanium and diamondlike carbon.