FIELD-EMISSION CHARACTERISTICS OF A CARBON NEEDLE MADE BY USE OF ELECTRON-BEAM-ASSISTED DECOMPOSITION OF METHANE

Very fine and thin needles are fabricated by use of the electron-beam-assisted reaction of methane diluted in hydrogen. The deposition apparatus is a conventional scanning electron microscope (SEM) modified to be able to introduce a gas into the specimen chamber up to 200 Pa. The field emission current from the carbon needle was more stable than that from tungsten field emitters. The current fluctuations were fundamentally step- and spike-like, which is characteristic for the field emission current of emitters such as carbon, carbides, and nitrides. The emission patterns were basically random, and show no systematic crystalline structures.