Field emission measurements with mu m resolution on chemical-vapor-deposited polycrystalline diamond films

The distribution of held emitting sites on polycrystalline diamond films at electrical surface fields has been investigated between 2.5 and 150 MV/m by means of a field emission scanning microscope with mu m resolution. For the first time field emission scans were performed on broad-area (approximate to cm(2)) diamond cathodes with in situ scanning electron microscope analysis of the localized sites. The 2-3-mu m-thick diamond films were chemical-vapor deposited on Mo substrates by the hot-filament technique. Undoped and p-type boron-doped films with low content of sp(2)-bonded carbons were studied. The highest emitter density of similar to 2000/cm(2) at 100 MV/m was detected on undoped diamond surfaces. A preliminary study of localized emitters indicated both sporadic particles of foreign materials at the emitting sites as well as intrinsic emission from diamond. In addition, the Fowler-Nordheim parameters beta and S, the elemental composition, and the current stability of localized emitters were measured. (C) 1996 American Vacuum Society.