The activation energy for the diffusion of isolated Pb adatoms on (111) Ge surfaces was deduced by means of scanning tunnelling microscopy. It was found that diffusion occurred mainly along one direction of the c(2 x 8) reconstructed surface, with adatoms moving between substitutional Ge adatom sites. Only half of the adatom interchanges were made to near-neighbor sites, while the remainder were long jumps. It was noted that the scanning process did not affect the diffusion process. At temperatures of between 24 and 79C, the diffusion data (ranging from 2 x 10-4 to 5 x 10-3 jumps/s/atom) could be fitted by an Arrhenius law, with an activation energy of 0.54eV.

E.Ganz, S.K.Theiss, I.S.Hwang, J.Golovchenko: Physical Review Letters, 1992, 68[10], 1567-70