DIFFUSION OF A SI ATOM ON THE SI(001)-2X1 SURFACE - A MONTE-CARLO STUDY

We use a modified form of the Stillinger-Weber potential to obtain the adsorption sites of a silicon atom on the fully relaxed Si(001)-2 X 1 surface. The barriers between sites are also found and these are used to estimate the rates of hopping from site to site. We conclude that the direction of easy diffusion is parallel and to the side of the dimer rows. The effective activation energy for the resultant quasi-one-dimensional motion (approximately 0.33 eV) is compared with recent experimental estimates. Our results also explain the appearance of regular island growth at high temperature as well as low-temperature "diluted-dimer" growth.