Emission confinement on the (100) planes of etched tungsten field emitters coated with thin-film ZrC

Field emission measurements were made on single crystal tungsten (100) emitters and were compared to emission measurements after coating with thin-film of zirconium carbide. The tungsten emitters were prepared using standard techniques. The emitter was then heated in steps with associated recording of emission data and images. The results showed a very marked emission confinement to the (100) crystallographic plane after coating with ZrC. The confined emission current was stabilized after falling to a lower lever. In a second set of experiments, (100) tungsten emitters were coated with NbC and ZrC in a separate deposition system and were placed in a 500 nm gate. The emitter were run at room temperature and at round 1800 K, emission confinement was again found on the (100) crystallographic plane. Emission stability was improved when the emitter was run at elevated temperatures. This research provided a method to obtain high current density field emission from a single tungsten tip coated with thin carbide film.