Field emission characteristics from grains and polycrystalline films of phosphorus-doped diamond grown by chemical vapor deposition

Polycrystalline diamond films are prepared on Si substrates with various,growth times by means of hot-filament chemical vapor deposition. Phosphorus atoms are doped as donor impurities. Field emission characteristics of diamond films are measured. Neither the film thickness nor the surface roughness has any influence on the field emission characteristics: The experimental results suggest internal electron emission from the Si substrate into the conduction band of the diamond. Moreover, it is found that the electron emission from diamond grains occurs at a lower electric field in comparison with that from diamond films.