Simulation of the cathode surface damages in a HOPFED during ion bombardment

Most vacuum devices are hampered by ion bombardment due to residual gases. Sometimes, it causes the breakdown of devices and shortens their life. In this article, the effect of the ion bombardment on the cathode surface in a structure of a field emission display was simulated. In this structure, a special type of spacer was used, named “hop” and “flu” spacer. The trajectories of electrons emitted by a cold cathode were calculated under influence of an electric field. From these calculations, the ionization of a residual gas and the corresponding trajectories of the positive ions were estimated. In this article, we modeled Si microtip and Mo microtip field emitters. Because inert gases are not easily absorbed by the getter, several different types of residual gases, such as neon, argon, krypton, and xenon, were introduced in the simulation. The simulation results show that ion bombardment damages on a silicon target induced by Ar, Kr, and Xe are more destructive than Ne. Also, Ar, Kr, and Xe are shown to be more destructive than Ne to a molybdenum microtip. The results obtained in this article suggest damage on Si is larger than that on Mo under the same ion bombardment and that a molybdenum emitter is more stable than a silicon emitter in a nonideal vacuum environment. © 2005 American Vacuum Society. DOI: 10.1116/1.2134720