Enhanced field emission from carbide-coated field emitters, and device applications

There is great interest in vacuum microelectronic devices using large compact field emitter arrays (FEAs), particularly flat panel displays and microwave devices. FEAs made of Mo or Si have been used in most cases. However, both materials have characteristics which limit FEA performance in devices. At LRI we have studied other FEA materials which may enable superior performance, particularly refractory carbides of transition metals such as ZrC. Our experiments demonstrate and quantify significant advantages, particularly reduced work function, more stable emission, greater tolerance of a degraded environment, high emitted current capability, and resistance to ion bombardment. With appropriate treatment and processing, it is possible to largely retain the advantages of carbides, either bulk emitters or thin coatings on Mo substrates, after exposure to air.