Cold cathode field emission using both Al-resin and Au-resin coatings on a tungsten substrate

Abstract

Recent efforts have been made towards improving the fabrication technology of a fine-tip tungsten cathode covered with a thin film(~ 0.2 μm thickness) of insulating resin. An intermediate very thin layer of either Al or Au was evaporated between the metal core and the insulator to form a new type of cathode consisting of a metal-metal-insulator-vacuum (M-M-I-V) system. To examine the performance of this composite cathode and to compare it with that of previously tested metal-insulator-vacuum (M-I-V) systems, tests were conducted. The results obtained demonstrated several agreements, such as the switching phenomena of the emission (at higher applied fields) and the follow-up hysteresis effect in the current-voltage characteristics. Some marked differences were also recorded such as the field emission pattern. Heat treatment resulted in general improvement of the stability of the emission which is a further evidence of how the emission characteristics are influenced by temperature.