Theoretical Study of Hydrogen Effect in Diamond Film Growth

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To clarify the reason why the growth of diamond film is achieved under the room temperature and atmospheric pressure by CVD method, and to study the mechanism of crystal growth for new meterials from the view point of computational physics, these are the aim of the research.We focused our attention to the necessity of hydrogen atmosphere for the diamond growth. We optimized the system, in which the adatom is moved from above to the center of the dimer on hydrogen-terminated (100) diamond surface, in a quasi-static way. The results shows that the terminating hydrogen atom removes from the surface, as the adatom adsorbs, and terminates the dangling bonds of the adatom. This process shows the surfactant effect of the carbon atom. These results are contrasted with the case of silicon surface. We interpreted the results from the facts that the carbon atom prefers sp^2 bonding whereas the silicon atom prefers sp^3 bonding, and the relation of electron affinities of carbon and silicon atoms relative to hydrogen atom, e_c>e_H>e_<Si>.