Migration of various important species (H, CH3, CH2, C2H, C2H2) on a diamond (111) surface was investigated theoretically, using a cluster approach and the second-order Møller-Plesset perturbation theory. The order of the energies (barriers) obtained for a single jump between two neighboring radical sites was CH2 < H < C2H ≈ CH3 (52, 248, 350 and 353kJ/mol, respectively). The C2H2 species was assumed to migrate by an alternating one-fold and di-fold site adsorption to the surface. The corresponding barrier obtained for C2H2 was 186kJ/mol, which was somewhere in between that of CH2 and H. The present type of surface migration of chemisorbed species will, with one exception, be energetically favorable in comparison to any desorption process. In the case of C2H2, a desorption process will be energetically favorable.

Surface Migration during Diamond Growth Studied by Molecular Orbital Calculations. Larsson, K., Carlsson, J.O.: Physical Review B, 1999, 59[12], 8315-22