Morphology and field emission properties of nano-structured nitrogenated carbon films produced by plasma enhanced hot filament CVD Original Research Article

Crystalline nitrogenated carbon (C:N) films have been successfully synthesised by hot filament chemical vapour deposition (HF-CVD) and plasma enhanced HF-CVD. Nitrogen gas (N2) and ammonia (NH3) were used as sources of atomic nitrogen whereas methane (CH4) acted as carbon precursor. Structure analysis reveals the growth of a new type of C:N films characterised by various polymorphs including worm-like features and foil-like structures at the nanometre scale. The effects of bias voltage and filament temperature on the film morphology are investigated in detail. The dependence of nucleation on the substrates, including pure Si and Ni-coated wafers, was studied. The presence of Ni was found to initiate the growth of arrays of nanotubes. Field emission in vacuum was observed on C:N films deposited on pure Si above applied fields of 20 V/μm. The onset field could be decreased below 3 V/μm with Ni-coated substrates due to the presence of well-separated nano-tubular structures.