An approach to the preparation of a tip-type of field emitter that is made up of carbon nanotubes (CNTs) coated with amorphous carbon nitride (a-CN(x)) films is presented for the purpose of enhancing its electron emission property. CNTs were directly grown on nano-sized conical-type tungsten tips via the inductively coupled plasma-chemical vapor deposition system, and a-CN(x) films were coated on the CNTs using an radio frequency magnetron sputtering system. The morphologies and microstructures of the a-CN(x)-coated CNTs were analyzed via field emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, high-resolution transmission electron microscopy, and x-ray photoelectron spectroscopy. The electron emission properties of the a-CN(x)/CNT hetero-structures were measured using a high-vacuum field emission measurement system. The best field emission properties, such as a very low turn-on voltage of 500 V and a maximum emission current of 176 mu A were achieved for the CNT emitter coated with the 5 nm-thick a-CN(x) film. In addition, this emitter showed a highly stable behavior in long-term (up to 25 h) electron emission. (C) 2011 Elsevier B.V. All rights reserved.