The potential energy surface for the migration of an extra Ga atom on the GaAs(001) β2(2x4) surface was mapped out by performing calculations at the level of an analytical bond-order potential. Based upon these calculations, some lower-energy sites were found, for the adsorption of an extra Ga atom in the surface, which were in agreement with the experimental data. Moreover, many possible pathways for an extra Ga atom diffusing in this surface were revealed. According to the relative energies of the possible pathways, the individual Ga adatoms preferably kept their diffusion to 2 pathways parallel to the As dimers. This result could be understood by using the strain caused by the diffusing Ga atom in the pathways. In addition, the simulated kinetic processes of the extra Ga atom diffusing in different pathways at finite temperatures supported the prediction from the calculated potential energy surface.

Diffusion of an Extra Ga Atom in GaAs(001)(2x4) Rich-As Surface. K.Li, B.Pan: Chinese Journal of Chemical Physics, 2008, 21, 69-75