X-ray photoelectron spectroscopic study of magnetron sputtered carbon-nickel composite films

Carbon-nickel films were deposited by direct current magnetron sputtering in argon plasma at temperatures between 25 and 800 degrees C. The films have a composite structure. consisting of a nanocrystalline dispersed phase embedded in an amorphous carbon matrix as revealed by high resolution transmission electron microscopy. Based on selected area electron diffraction, the crystalline phase was assigned to hexagonal nickel carbide (Ni3C) for films grown below 400 degrees C and to face centered cubic nickel for those prepared above 400 degrees C. X-ray photoelectron spectroscopic studies verify these results. In films deposited below 400 degrees C the carbon Is spectral range contains two low binding energy components at 283.2 and at 281.5 eV (+/- 0.2 eV). While the peak at 281.5 eV corresponds to the carbidic environment, the component at 283.2 eV, existing also in high temperature samples, is assigned to carbon atoms constituting the interface between the carbon matrix and the Ni3C or Ni crystallites. (C) 2008 Elsevier B.V. All rights reserved.