Diffusion of hydrogen on the Si(001) surface investigated by STM atom tracking

The scanning tunneling microscopy atom-tracking technique is used to follow the individual diffusive hops of single H and D atoms on the Si(001) surface in ultrahigh vacuum. Attempt frequencies and activation energies for diffusion along the dimer row (intrarow) and between the atoms of a single Si dimer (intradimer) are extracted. For intrarow H diffusion, an activation energy of 1.75+/-0.10 eV and an attempt frequency of 10(14.5+/-0.8) Hz are found. For intradimer H diffusion, an activation energy of 1.01+/-0.05 eV and a low attempt frequency of 10(10.3+/-0.5) Hz are found. The ratios of H to D attempt frequencies for intradimer and intrarow diffusion are also determined. [S0163-1829(99)10247-9].