Better than 10 mA field emission from an isolated structure emitter of a metal oxide/CNT composite.

An isolated structure emitter is presented that can deliver a field emission better than 10 mA, a level that is by far the highest ever reported. A composite of CNT (carbon nanotube) and WO(3) is used to grow the point emitter by a crystal-like growth technique. The head of the grown needle that is the emitter is removed by electric discharge machining (EDM). The EDM treatment not only controls the length of the emitter as desired but also makes the tip of the emitter uniform. The thermal heat due to EDM treatment leads to the formation of a tungsten carbide phase, which results in a 3 orders of magnitude reduction in contact resistance. The point emitter is robust in its stability, as evidenced by its on-time resilience against a severe bias test.