GRAPHENE COLD FIELD EMISSION SOURCES FOR ELECTRON MICROSCOPY AND LITHOGRAPHY APPLICATIONS

Abstract

Cold field emission sources are capable of providing highly coherent and bright electron beams. However, they suffer from some well-known practical difficulties that have prevented their widespread use: unmanageably stringent UHV requirements, relatively large current instabilities, and rapid emission decays. This work presents the development of a completely new type of electron source, a graphene-coated point cathode. The results establish the promising prospect of using them as high brightness-high resolution electron sources, similar in performance to the state-of-art tungsten sources, while at the same time having better emission stability and less stringent vacuum requirements. Another original development coming from this work is the microfabrication and successful emission test of a micron-sized concentric graphene ring-cathode cold field emitter. This type of electron gun can be used in focused beam columns to image ring patterns on a sample directly, without the need to employ a projection mask or a scanning unit.