The migration mechanism of Al atoms on (001) surfaces was investigated by performing theoretical calculations using the molecular-orbital method within the semi-empirical approximation and/or the first-principles method, using density-functional theory. The calculations were performed for 3 types of surface: a 2 x 1 reconstructed clean surface, a H-terminated 2 x 1 monohydride surface and a partly H-terminated surface. The lowest potential-energy paths for Al adatom migration were determined for these surfaces. The activation energy which was required for Al diffusion on the clean surface was estimated to be 0.7eV, whereas the energy that was required for diffusion on the H-terminated surface was of the order of 0.001eV. Moreover, the transfer of an Al adatom from H-terminated to non-terminated regions occurred spontaneously, with an energetic stabilization of over 3eV.

Migration of an Al Adatom on the Clean H-Terminated or Partly H-Terminated Diamond (001) Surfaces. T.Hoshino, K.Yamazaki, S.Sagiyama, M.Hata, M.Tsuda: Physical Review B, 1999, 60[7], 4810-5