Using Zn powder as the raw material, Tetrapod-like ZnO nanoneedles with controllable morphology and size were successfully prepared by chemical vapor deposition. A screen printed normal-gated triode with Tetrapod-like ZnO nanoneedles field emitters is demonstrated. Field emission measurements show that the Tetrapod-like ZnO nanoneedles FED triode devices posses a good field emission property. The turn-on voltage is 270V. An anode current of 2.75 mA and a gate current of 0.43 mA are extracted at a gate voltage of 600 V with a brightness of 2300 cd/m2.
