The saturated monohydride surface was imaged at between 600 and 700K by using high-temperature scanning tunnelling microscope, and the concerted diffusion of pairs of H atoms along the dimer rows was observed. The barrier for this process was estimated, from the scanning tunnelling microscopy data, to be equal to 1.95eV. On the basis of the images, the mechanism was narrowed down to the consideration of 2 possible routes. Only one of these routes involved a barrier (1.98eV) which was consistent with experimental data; thus permitting the conclusive identification of the diffusion mechanism.

Diffusion of Paired Hydrogen on Si(001). D.R.Bowler, J.H.G.Owen, K.Miki, G.A.D.Briggs: Physical Review B, 1998, 57[15], 8790-3