The energetics and diffusion barriers of arsenic and gallium adatoms on smooth and stepped GaAs (001) surfaces were investigated (table 27). Energy minimization with the Tersoff potential was used to calculate the adiabatic potential experienced by an adatom. For smooth surfaces, the most stable structures that were important for molecular-beam epitaxial growth conditions were considered. For these, the potential surfaces were mapped and the diffusion paths over the lowest saddle-points were identified. In the case of stepped surfaces, the two simplest kinds of straight step were considered: A and B steps on the (001) surface. For gallium adatoms, evidence was found for a step-edge barrier for B steps, but no barrier for going down the A step, and no barriers to arsenic adatoms.

Energetics and Diffusion Paths of Gallium and Arsenic Adatoms on Flat and Stepped GaAs(001) Surfaces. Salmi, M.A., Alatalo, M., Ala-Nissila, T., Nieminena, R.M.: Surface Science, 1999, 425[1], 31-47