Enhanced field emission properties of ZnO nanorods by surface modification

Abstract

ZnO nanorods on Si substrates have been synthesized by a simple vapor phase transport method. A two-step surface modification, which involves coating with a very thin AlN layer followed by Ar⁺ plasma etching treatment, has been employed to enhance the field emission (FE) properties of ZnO nanorods. Compared with the FE properties of as-grown ZnO nanorods, the turn on field of the two-step surface modified ZnO nanorods decreased to 42% from 16.0 to 6.8 V μm⁻¹ at the current density of 10 μA cm⁻², and the FE current density increased by about 40 times, reaching as high as 4.1 mA cm⁻² at an electric field of 17.4 V μm⁻¹. It has been proposed that the enhancement in the field emission properties is due to the reduction of the effective work function and the low electron affinity of the thin AlN coating layer, as well as the enhanced local field near the reduced tips of the ZnO nanorods. This study provides an effective approach for enhancing the FE properties of semiconductor emitters.