Substitution of diamond with insulator in nanostructured carbon low-field emitters

It was found that diamond structures such as CVD diamond films and diamond/carbon composites can show outstanding low-field electron emission properties with threshold fields of 1-3 V//spl mu/m. Numerous microscopic studies of the emission centers show that the emission is associated just with diamond grain boundaries, diamond/sp/sup 2/ -bonded carbon interfaces and thin conducting carbon layers covering the diamond particles and placed between the diamond grains. However, a role of the diamond phase for the emission is still not clear enough. In particular, the Negative Electron Affinity (NEA) of diamond is often considered as one of the origin of the excellent field emission.