INFLUENCE OF STRUCTURAL AND MORPHOLOGICAL PROPERTIES ON THE INTRINSICFIELD-EMISSION OF CVD DIAMOND FILMS

The ''intrinsic'' field emission properties of CVD diamond films, grow n in a microwave plasma chemical vapour deposition setup, were investi gated. The substrate temperature, content of methane and nitrogen in t he process gas and the bias voltage were systematically varied. Parts of some samples were intentionally damaged by C-ion implantation, Morp hological and structural properties of the films were analysed by scan ning electron microscopy (SEM) and Raman spectroscopy. Field emission (FE) properties were measured by means of a field emission scanning mi croscope with a resolution of 1 mu m. All samples showed an ''intrinsi c'' FE over those parts of the surface, on which ''parasitic'' FE, e.g . dust particles, could not be detected by in-situ SEM. The ''intrinsi c'' electrical onset field strength (E-on) varied from 245 to 1000 MV m(-1). Significant differences in non-diamond content (e.g. amorphous carbon, graphite) had no or little influence on the FE strength. Howev er, the surface morphology was correlated with E-on, suggesting geomet rical field enhancement by rough micro structures, The electron potent ial barrier was located at the surface for good conducting films. In c ontrast, the barrier of an insulating film was located at the substrat e-diamond interface, indicating an alternative emission mechanism. (C) 1998 Elsevier Science S.A.