The Ga adatom adsorption and diffusion processes on the GaAs(001)-c(4 x 4) surface were studied using ab initio density-functional-theory computations in the local density approximation. Two distinct sets of minima and transition sites were discovered for a Ga adatom relaxing from heights of 3 and 0.5 Å from the surface. These two sets showed significant differences in the interaction of the Ga adatom with surface As dimers. An electronic signature of the differences in this interaction was identified. The energetic barriers to diffusion were computed for various adsorption sites. From these, three pathways for diffusion of a Ga adatom on this surface were deduced which indicated anisotropic diffusion along different directions.

Binding Sites and Diffusion Barriers of a Ga Adatom on the GaAs(001)-c(4×4) Surface from First-Principles Computations. J.L.Roehl, A.Kolagatla, V.K.K.Ganguri, S.V.Khare, R.J.Phaneuf: Physical Review B, 2010, 82[16], 165335