SUBSTITUTIONAL NITROGEN DOPING OF TETRAHEDRAL AMORPHOUS-CARBON

Amorphous carbon films prepared by filtered cathodic arc deposition have been studied by electron-energy-loss spectroscopy. It is shown nitrogen concentrations in the film of up to 30 at.% can be controllably introduced. For nitrogen concentrations of up to 2-3 at.% the films are primarily sp3 bonded, whilst films with higher nitrogen concentrations are primarily sp2 bonded. It is shown that the nitrogen is substitutionally incorporated into both the sp3 and the sp2 carbon networks. The presence of nitrogen in the films with a high sp3 fraction leads to a sensitivity to conversion to the sp2-rich form in a 300 keV electron beam.