DIFFUSION OF SI ATOMS AND DIMERS ON SI(100)

Activation energies for diffusion of Si adatoms and dimers on a Si(100) surface are estimated through computer simulations. The potential field is probed by forcing an adatom to move adiabatically, while the surrounding atoms relax. The Stillinger-Weber potential is used. It is found that (1) the diffusion barrier height for an isolated adatom is smaller than that for a dimer; (2) the activation energies are comparable for the two atoms in a dimer to hop together or to separate from each other; (3) the activation energies of an isolated dimer, a dimer sitting next to a dimer chain, and a dimer at the end of a dimer chain are almost identical, despite differences in the binding energies.