Abstract
The electron emission mechanism of a cathode covered with carbon-based hard film is discussed in relation to thermionic electron emission. This new model can reproduce the frequently observed peculiar Fowler-Nordheim plots consisted of two distinct parts, which are a strong electric field dependent part and a very weak field dependent part. It is shown that there is a relationship between the threshold electric field and film thickness as well as the threshold electric field and anode-cathode distance. The present model requires neither special field-enhancement mechanisms nor extremely small work function but does require retarding potential at dielectric-film/vacuum interface (∼1 eV).
