Scanning tunnelling microscopic atom-tracking was used to monitor the individual diffusive hops of single H and D atoms on the (001) surface under ultra-high vacuum. The attempt frequencies and activation energies for diffusion along a dimer row (intra-row) and between the atoms of a single Si dimer (intra-dimer) were deduced. In the case of intra-row H diffusion, an activation energy of 1.75eV and an attempt frequency of 1014.5Hz were found. For intra-dimer H diffusion, an activation energy of 1.01eV and an attempt frequency of 1010.3Hz were found.

Diffusion of Hydrogen on the Si(001) Surface Investigated by STM Atom Tracking E.Hill, B.Freelon, E.Ganz: Physical Review B, 1999, 60[23], 15896-600