The formation of atomic steps in chemical vapour deposition diamond growth

A mechanism for the formation of atomic steps in chemical vapour deposition diamond growth is proposed. First, a number of groups is adsorbed on the diamond (111) surface, each of which consists of three neighbouring methyl radicals, and there are small steric repulsions among these groups because of the large distances between them; second, the three CH3 radicals in each of the groups are bound to form the step diamond structure via H abstraction of hydrogen atoms and CH3 radical intermediates. The epitaxial growth possibly proceeds on addition of a certain species, such as C2H2 or CH3 addition, until it encounters another step structure from epitaxial growth of another group of CH3 radicals. Once the atomic steps are flattened, the process will be repeated again. This mechanism is supported by the results of first-principles discrete variational method calculations and is consistent with the conclusions reported in the literature.