Chemical bond analysis of amorphous carbon films

Hydrogen-free carbon films with the various sp3 bond fractions between 83% and 40% were prepared by mass-separated ion beam deposition (MSIBD). These sp3 bond fractions were obtained by electron energy loss spectroscopy (EELS). Chemical bond analysis of these carbon films was performed by x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and Raman spectroscopy, and the comparison of these methods was examined. XPS C1s spectra of carbon films show two contributions at the energies of 284.5 and 285.5 eV, which are originated from sp2-bonds and sp3 bonds, respectively. The sp3 bond fractions obtained by XPS are in good agreement with the values given by EELS. The fine structure of AES spectra at the kinetic energy region between 245 and 265 eV reflects the sp3 bond fraction. AES spectra are changed from the diamond-like feature to the graphite-like one with decreasing the sp3 bond fraction. Raman spectra show two broad peaks of G band and D band, the ratio of two peak intensities is independent on the sp3 bond fraction of films. The shift of G peak position has a correlation with the sp3 bond fraction in the sp3 bond rich region.