Thermal adatoms which were present at the surface at high temperatures and were in equilibrium with step-edges were recalled to be of key importance in mediating dynamic phenomena such as step capillary wave motions, epitaxial growth, surface phase transitions, and the decay of non-equilibrium structures by surface diffusion. Here, the first direct measurements were made of the thermal adatom concentration on Si(001) at high temperatures. From the results, it was deduced that the adatom formation energy was 0.35eV. A comparison with first-principles theory showed that the adatoms occurred as dimers.

Thermal adatoms on Si(001) R.M.Tromp, M.Mankos: Physical Review Letters, 1998, 81[5], 1050-3