Study On The Growth Of Nano-Carbon Films By CVD

In this dissertation, extensive researches on the electrical and field emission properties of nano-carbon films prepared by hot filament chemical vapor deposition (HFCVD).On the base of introduction, in which the discovery, physical properties and using will be outlined, the growth mechanism of diamond, which prepared by hot filament chemical vapor deposition was analysed. The factors, which may affect the production of diamond films, have been discussed, such as source of carbon in gas, substrate in solid and active hydrogen molecules and atoms. The density of nucleation and growth rate has been calculated by thermodynamic and statistical theory, and critical nucleation size and nucleation rate were obtained. The experimental equipment that prepared nano-carbon films by hot filament chemical vapor deposition has been described. Using the computer simulation, radiant field and temperature field was theoretically calculated. The distribution of temperature on the substrate was also been drawn. For hot filament array, seasonal distribution and uniformity of temperature have been shown. Conductance was calculated by Boltzmann equation, including island structure, non-continuum and continuum films. The Schottky emission model has been compared with tunnel emission model by the calculation of the conductance of non-continuum film. The sample prepared by CVD was analysed by scanning electron microscopy (SEM) and X-ray diffraction. The resistance of graphite carbon films were measured and drawn the curves which are the changes in resistance with substrate temperature and methane concentration in Ha, The experimental results showed that the films resistance was decreased with the increasing methane concentration, the other hand, it increased with the increasing temperature. The field emission properties were studied, and the work function, actual emission area and density of emission spot were calculated. The measurements at different areas showed good field emission characteristics and uniformity. That means the emission is follow the rule of spot emission, and emission spot depended on distribution uniformity in the films, so it showed the macroscopical homogeneous emission characteristics.