Spindt tip composed of carbon nanotubes

We report the synthesis of a cone-shaped bundle composed of carbon nanotubes (CNTs) in the gate holes by a multi-step growing method: (1) growth of carbon nanotubes in the gate hole; (2) etching the grown CNTs by in situ plasma treatment; (3) regrowth of CNTs. The new CNT bundle in the gate holes exhibited a turn-on gate voltage of 23.5 V, an anode current density of 0.034 mA cm2 at the gate voltage of 30 V, and a transconductance of 2.05× 10-4 S; these are about 50% enhancement compared to conventional CNTs. The field emitter array with the Spindt-type CNTs in the gate holes shows uniform light emission.