Field emission from diamond, diamond-like and nanostructured carbon films

We have deposited nanotube films on silicon via a chemical vapor deposition (CVD) growth process known from the deposition of diamond. We used a metal lic catalyst which was deposited onto the silicon surface prior to the CVD deposition. The films are very pure, adhere well and are very well suited f or electron field emission. We measured emission at 2.6 V/mu m (for 1 nA em ission current) and an emission site density reaching 10(4)/cm(2) at 3-4 V/ mu m as measured on a phosphor screen. Electrons originate at the Fermi lev el and the high local fields at the emission site is produced by the geomet ry of the nanotube. The results obtained on these films are comparable to t hose from differently prepared CVD diamond films. So far, we have no eviden ce that electron injection occurs. The emission process is governed by fiel d amplification at protrusions and tips. In a second experiment we have mea sured emission from a metallic micrometer sized grain fixed on a diamond (1 00) surface, with different surface termination (hydrogen, oxygen, sp(2) ca rbon). The field emitted electron energy distribution (FEED) spectra show l arge energy shifts which are due to the surface resistivity and not due to injection of electrons in the conduction band. Hence, energy shifts in FEED spectra do not necessarily reflect an injection mechanism. (C) 1999 Elsevi er Science Ltd. All rights reserved.