Variation of bonding structure near the surface of carbon nitride films

Amorphous carbon nitride (a-C:N) films were deposited by reactive direct cu rrent magnetron sputtering of graphite using a gaseous mixture of Ar and N- 2. X-ray photo electron spectroscopy analysis (XPS) showed that there is an optimum volume ratio of nitrogen:argon in the sputter gas that results in a maximum content of incorporated nitrogen in the films. By using different take-off angles in XPS experiments, the variation gradient of bonding stru cture near the surface of a-C:N films has also been studied. In the surface layer of the a-C:N films, it was found that some of the initially formed b eta-C3N4-like phase transforms to a graphite-like carbon-nitrogen phase. Th is structural change is driven by the nitrogen in the sputter gas during de position. (C) 2000 Elsevier Science B.V. All rights reserved.