COMPARISON OF ELECTRIC-FIELD EMISSION FROM NITROGEN-DOPED, TYPE LB DIAMOND, AND BORON-DOPED DIAMOND

Field emission of electrons from boron- and nitrogen-doped diamond is compared. Emission from boron-doped diamond requires vacuum electric f ields of 20-50 V mu m(-1), while nitrogen-doped, type Ib diamond requi res fields of 0-1 V mu m(-1). Since boron-doped diamond is very conduc tive, very little voltage drop occurs in the diamond during emission. Nitrogen-doped diamond is insulating, so during emission a potential o f 1-10 kV appears in the diamond. This potential is a function of the back contact metal-diamond interface. A roughened interface substantia lly reduces the potential in the diamond and increases emission. The e lectrons are often emitted from the nitrogen-doped diamond as beamlets . These beamlets leave the surface of the diamond at angles up to 45 d egrees from the substrate normal. Although the vacuum field is small, these electrons have energies of several kV. It is unknown whether the electrons are accelerated to these energies in the bulk of the diamon d, or at high electric fields near the emitting surface. (C) 1996 Amer ican Institute of Physics.