FIELD-EMISSION MEASUREMENTS WITH MU-M RESOLUTION ON CHEMICAL-VAPOR-DEPOSITED POLYCRYSTALLINE DIAMOND FILMS

The distribution of held emitting sites on polycrystalline diamond fil ms 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 re solution. For the first time field emission scans were performed on br oad-area (approximate to cm(2)) diamond cathodes with in situ scanning electron microscope analysis of the localized sites. The 2-3-mu m-thi ck 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 den sity of similar to 2000/cm(2) at 100 MV/m was detected on undoped diam ond 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 stab ility of localized emitters were measured. (C) 1996 American Vacuum So ciety.