Field electron emission of nano-structure carbon based thin films

Nano-crystalline fullerene-like film, nano-crystalline graphitic film and nano structure amorphous carbon film were prepared by microwave plasma chemical vapor deposition (MPCVD). The nano-structure and surface morphology of the deposited films were identified by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman scattering and scanning electron microscope (SEM). The field electron emission characteristics of the films were studied by a testing method of diode structure in a vacuum chamber. The deposited nano-structure carbon based thin films and phosphor coated indium tin oxide (ITO) film were used to be cathode and anode, respectively. At the initial measurement, a very low turn-on field of 0.6V//spl mu/m was obtained for the three kinds of nano-structure carbon based materials. After cycling of voltage up and down several times, the turn-on field went up to more than 1.0 V//spl mu/m, and the current density decreased. In this paper, we suggest a theoretical model to discuss the field electron emission mechanism for the nano-structure carbon based thin films, and explain the emission characteristics. The surface local states, the bond dangling of carbon atoms and adsorbates on the surface of the films were considered in the theoretical model.