Maximized sp3 bonding in carbon nitride phases

Carbon nitride films were deposited using a low pressure, dual ion beam system consisting of a filtered cathodic vacuum arc and a plasma beam source for carbon and nitrogen ions, respectively. This system maintains highly ionized beams even at high nitrogen fluxes, unlike in single beam systems. Film composition and bonding were measured by electron energy loss spectroscopy. Films with nitrogen to carbon atom ratios (N/C) up to 0.5 are produced. The carbon bonding is found to change gradually from sp(3) to sp(2), rather than sharply above a critical N content, as found previously. This indicates that N atoms form individual C=N bonds rather than causing a reversion of the entire C network to sp(2). This allows us to maintain C sp(3) bonding to the highest N contents so far achieved. (C) 2000 American Institute of Physics. [S0003-6951(00)05336-5].