Enhanced field emission performance of ZnO nanorods by two alternative approaches

Standard ZnO nanorods with a diameter of similar to 150 nm show poor field emission performance. In an attempt to dramatically improve the field emission properties, we developed two alternative methods: The first one is to decrease the tip radius of nanorods down to similar to 5 nm. The second one is to decorate the nanorods by small metal particles. By either of these two approaches, we can obtain excellent field emission performances, typically turn-on field (the electric field at which the current density reaches 10 mu A/cm(2)) as small as 2 V/mu m and current density as large as 1 mA/cm(2) can be readily achieved. The physical essence of the excellent performances is the geometrically enhanced local field near the tip of the nanorods and the lowered work function of ZnO nanorods by the donation of electrons from the nanoparticles.