Enhanced field-emission from a mixture of carbon nanotubes, ZnO tetrapods and conductive particles

We report the enhancement of field-emission current from a mixture of carbon nanotubes, ZnO tetrapod-like nano structures, and conductive particles. Carbon nanotubes are deposited on the electrode as the field emitters. A MgO layer is printed around the cathode electrode, and ZnO tetrapod-like nano structures are deposited on this layer for the generation of secondary emission electrons. A few conductive particles are also distributed on the MgO layer by spraying or screen-printing. These conductive particles enhance the transverse electric field around the cathode electrode. Consequently, more primary electrons emitted from the carbon nanotubes bombard on the ZnO tetrapods, and secondary emission electrons and scattered electrons are yielded. Finally, the field-emission current is enhanced obviously. As experimental results shown, a high field-emission current about 32 mA in a direct current emission mode has been obtained from a 0.5 cm2 emission site when an electric field of 9 V/microm is applied between cathode and anode. Compared with a conventional carbon nanotube cathode, the field-emission current has been improved about 80%.