Field Electron Emission from the Tip of a Graphite Fiber

Usually carbon wires cannot be used for obtaining remarkable field electron emission because the difficulty of sharpening its tip with a sufficient small radius of curvature to fit the electrical field. However, a large number of small fragments are formed on tips of graphite fibers after a discharge treatment with 10 kV DC high voltage on graphite fibers. These fragments observed by SEM and HRFEM are spheres, flakes and needle-like nanostructures with the size around 50 nm. In this case, each of these spheres and flakes can be an emission center in field emissions and some detectable emission currents can be obtained with a low applied voltage. Experimental results show that a single graphite fiber of 20 mu m diameter can generate near 0.2 mA emission current with 4 kV applied voltage and the stability have been measured to be less than 10 %. It is expected that graphite fibers as a novel cold cathode material will provide a wide range of applications such as in flat panel displays, high-power and high-brightness vacuum electronic devices, and vacuum microelectronic devices.