Ion-beam morphological conditioning of carbon field emission cathode surfaces

Square-cm samples of bulk graphite, reticulated vitreous carbon, and paste graphite film have been evaluated for field-emission properties both before and after surface modification using a novel Ar-ion flood bombardment method. The Ar-ion treatment results in a change in surface morphology of the emission cathode which physically resembles results of emission treatments using lasers or other heat sources, as well as results obtained using current or voltage stress treatment methods. Emission properties become more uniform, exhibit less noise, and, in the best cases, match results seen from carbon nanotubes or ultra-nanocrystalline diamond cathodes. The results demonstrate a method for obtaining large total currents at optimal extraction voltages, from large-area, low-cost cathodes. This method is useful for applications, such as field-emission lamps and x-ray tubes, which do not require nanofabricated cathode structures.