Nano-structured nitrogenated carbon films - morphology and field emission

Crystalline nitrogenated carbon (C:N) films have been successfully synthesised by plasma-enhanced hot filament chemical vapour deposition (PE-HF-CVD). Nitrogen gas (N-2) and ammonia (NH3) were used as sources of atomic nitrogen whereas methane (CH4) acted as a carbon precursor. Structure analysis reveals the growth of a new type of ON film characterised by various polymorphs including worm- and foil-like microstructures at the nanometer scale. The effects of bias voltage and filament temperature on the film morphology are investigated in detail. Using pure Si as a substrate results in growth of homogeneous nanostructured films, whereas arrays of nanotubes were deposited on Ni-coated substrates. Field emission in vacuum was observed on C:N films deposited on pure Si above applied fields of 15 V/mum. The onset field could be decreased below 4 V/mum with Ni-coated substrates due to the presence of well-separated nano-tubular structures. (C) 2001 Elsevier Science B.V. All rights reserved.