Nano Preparation Of Amorphous Carbon Films And Their Field Electron Emission Properties

In this thesis the effect of experimental conditions of microwave plasma chemical vapor deposition system (MPCVD) on the field emission property of amorphous carbon films were studied, and nano-amorphous carbon films with low turn-on field and high field emission current density were prepared. The field emission mechanism and the relationship between film structure and field emission property were studied. The mechanism of field electron emission degradation of the films was also studied. At last, the work function changes of graphite (0001) surface due to hydrogen atom and hydrogen ion chemisorption on its surface at different adsorption sites and coverage were calculated by using density functional theory (DFT). The calculation results have been used to explain the experimental phenomena as an approximation. The specific research works were as following:1. The experimental conditions including microwave power, reaction pressure, source gasses and their flow rate were selected by the cross design experiment to deposited nano-amorphous carbon films on silicon substrates and ceramic substrates separately. The turn-on field of 1.0 V/μm was obtained, the current density reached to 2.0mA/cm~2 at the field of 3.0V/μm and the emission site density was more than 10~4/cm~2 for the film deposited on silicon substrate. The turn-on field of the film as low as 0.6V/μm was obtained, and the current density reached to 1.7mA/cm~2 at the field of 1.7V/μm for the film deposited on ceramic substrate. The results were better than that reported by some authors up to date. The measurement results of X-ray diffraction (XRD), Raman scattering spectroscopy (Raman), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) revealed that the films were composed of nano-structured amorphous carbon particles, the content of sp~2 carbon was more than 50% in the film deposited on silicon substrate and the film deposited on ceramic substrate was mainly sp~2 component.2. The field emission stability and microscopic field-emission characteristic of...