Field emission from diamond, diamond-like and nanostructured carbon films Original Research Article

We have deposited nanotube films on silicon via a chemical vapor deposition (CVD) growth process known from the deposition of diamond. We used a metallic 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 for electron field emission. We measured emission at 2.6 V/μm (for 1 nA emission current) and an emission site density reaching 104/cm2 at 3–4 V/μm as measured on a phosphor screen. Electrons originate at the Fermi level and the high local fields at the emission site is produced by the geometry of the nanotube. The results obtained on these films are comparable to those from differently prepared CVD diamond films. So far, we have no evidence that electron injection occurs. The emission process is governed by field amplification at protrusions and tips. In a second experiment we have measured emission from a metallic micrometer sized grain fixed on a diamond (100) surface, with different surface termination (hydrogen, oxygen, sp2 carbon). The field emitted electron energy distribution (FEED) spectra show large 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.