Field electron emission from a nickel-carbon nanocomposite

The field-emission properties of nanocomposite films comprised of 10 – 20 nm-sized nickel particles immersed in a carbon matrix were investigated. The films were deposited onto silicon substrates by means of a metalorganic chemical vapor deposition (MOCVD) method. The composite's structure was controlled via deposition process parameters. Experiments demonstrated that the composite films can efficiently emit electrons, yielding current densities of up to 1.5 mA/cm$^{2}$ in electric fields below 5 V/$\mu$m. Yet, good emission properties were only shown in films with low effective thickness, when nickel grains did not form a solid layer, but left a part of the substrate area exposed to the action of the electric field. This phenomenon can be naturally explained in terms of the twobarrier emission model.