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±0.8Hz are found. For intradimer H diffusion, an activation energy of 1.01±{}0.05 eV and a low attempt frequency of 10^10.3±0.5Hz are found. The ratios of H to D attempt frequencies for intradimer and intrarow diffusion are also determined.