Electron-energy-loss spectroscopy of mass-selected ion-beam-deposited diamondlike carbon

Amorphous diamondlike carbon (DLC) films grown by low-energy mass-selected ion-beam deposition have been examined by electron-energy-loss spectroscopy (EELS). Films grown using deposition energies of 50, 120, and 300 eV have been studied. For these deposition energies, all films exhibit similar EELS characteristics indicating a very high degree of sp3 bonding. The bulk plasmon resonance is intermediate between that of graphite and that of diamond; however, the properties of the low-energy-loss spectra of the DLC films are more similar to those of diamond. The near-K-edge carbon EELS data from the films exhibit a π* feature which is much smaller than that of graphite or evaporated carbon. The use of previously proposed computational methods on the near-K-edge EELS data indicates that over 80% of the carbon atoms are sp3 bonded. The size of the π* feature is larger for smaller plasmon energies, as expected. The present data are in accord with other analyses of similar films that indicate a broad (∼30–300 eV) energy window for diamondlike film formation.