Effect of nitrogen incorporation into diamond-like carbon films by ECR-CVD

Diamond-like carbon (DLC) and nitrogenated DLC (a-C:N) films were prepared on Si and glass substrates using an electron cyclotron resonance-assisted microwave plasma chemical vapour deposition (ECR-MPCVD) system with radio frequency substrate bias. The hardness and optical bandgap of the resulting films were investigated and correlated to the elemental and phase compositions. The a-C:N films, deposited under conditions identical to those for the DLC films except for the introduction of a nitrogen flow, contain nitrogen which partly substitutes for hydrogen and forms carbon-nitrogen triple bonds. These bonds obstruct the formation of carbon-carbon cross-linking, resulting in softer films. These changes can be interpreted with reference to various changes of active vibronic states determined by Raman spectroscopy. (C) 1999 Elsevier Science S.A. All rights reserved.