Vacuum microelectronics has attracted many research fields in electron beam devices due to high potential in their applications

such as field emission display

high frequency and high power devices

etc. An essential requirement among these devices is the development of a noble cathode which produces a stable

high density and uniform electron emission at low driving voltage. Diamond and related materials are the strong candidates as the cathode materials

because the relatively high brightness of field emission from diamond and diamond like carbon films have been observed at low field by the nitrogen doping and some surface treatment of the films

even though its emission mechanism is not clear. Some emission model had been suggested

however

further investigation to understand the emission mechanism of the materials is essential to develop a flat cathode for actual applications to FED and other vacuum microelectronic devices. The paper describes the fabrication of a plane cathode by plating a thin metal film on polycrystalline diamond film and forming a gated cathode with a planar diode structure. It shows an electron emission from the cathode at driving voltage as low as 10V

and the emanative angle of the emitted electrons is smaller than 6° observed from its image on fluorescent screen. In addition

the field emission from a high quality diamond particle shows hardly emissive due to a high barrier height at the interface between the diamond and the substrate which prevents electron injection into the diamond. The emission mechanism was discussed and suggested that the electron emission occurs probably from grain boundaries in a polycrystalline diamond film.