可低压驱动的金刚石薄膜冷阴极特性研究

Field Emission from Diamond Films by Low Voltage Driving

通过在金刚石薄膜表面沉积超薄金属薄膜作为栅极的方法,在10V左右的低压下观察到场发射现象,其发射电子的发散角度为10°左右,接近于面发射;而孤立的金刚石颗粒几乎观测不到场发射。金刚石薄膜的场发射可能来自晶间相。

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.