Synthesis and field electron emission characteristics of diamond multilayer films grown by graphite etching

Abstract

Diamond multilayer film with nanocrystalline diamond film coated on a layer of diamond nanocone film, was synthesized on silicon substrates by using in situ graphite etching in a hot filament chemical vapour deposition reactor. Many small and sharp protrusions on the surface of the multilayer film were observed using scanning electron microscope and atomic force microscope. The multilayer film exhibits lower turn-on field and larger emission current than flat diamond films and diamond nanocone films. Field electron emission measurements at different residual gas pressures indicate that emission current of the multilayer film shows no obvious degradation and the Fowler–Nordheim (F–N) plots parallel to each other when the residual gas pressure is increased from 10−7 to 10−5 Torr. At a higher pressure of 10−3 Torr, obvious degradation of emission current was observed. The slope of the F–N plot becomes larger, indicating that the work function is increased. The possible reason is that the surface of the multilayer film is fully covered by residual gas molecules.