Improvement of Turn-On Voltage by Thermal Annealing of a Tungsten Single Emitter Coated with a Carbonaceous Film Deposited in Liquid Methanol

A carbonaceous thin film was deposited on a tungsten single emitter by electrolysis of liquid methanol. The carbonaceous single emitter was thermally treated under vacuum conditions, and changes in its field emission characteristics were examined. The field emission characteristics obeyed the Fowler-Nordheim relationship for all annealing temperatures. The turn-on voltage decreased from 1640V to 790V with annealing up to 1373K.