Nanocrystalline diamond films grown in nitrogen rich atmosphere: structural and field emission properties

The field emission behaviour of a series of nanocrystalline N-doped diamond films has been investigated and interpreted on the basis of the structural and compositional characteristics of the layers. The diamond films, formed by crystallites with grain size in the range 20-100 nm were produced from CH4/H2 mixtures using a HF-CVD apparatus. Nitrogen was added to the gaseous reactants in form of both N2 and of Urea. Micro-Raman spectroscopy and cathodoluminescence have been used to define the structure of the deposits on a nanometric scale. The field emission measurements have been carried out under a pressure of 10(-6) mbar using a sphere-to-plane anode-cathode configuration. The characteristics of the emission from the various nanodiamond samples and from different regions of the same sample are discussed in terms of field threshold, current density, current stability.