The behavior of Ga adatoms on GaAs(n11)A (n = 2, 3, 4), (001)-(2x4)β2 and non-planar surfaces consisting of the (211)A and (001) were systematically investigated by ab initio-based approach and the Monte Carlo (MC) method. The ab initio total energy calculations clarify strong dependence of Ga adsorption energies on the surface index. Comparing these adsorption energies of Ga with the Ga chemical potentials in the vapor phase, Ga atoms predominantly adsorb on the (211)A and (311)A surfaces at high temperatures even beyond about 1100K. On the other hand, Ga atoms tend to desorb from the (411)A and (001) surfaces at the high temperatures. Furthermore, the MC simulations revealed that diffusion coefficient of Ga adatoms across the (001) surface was larger than that on the (211)A surface. This was because Ga migration potential energies on the (001) surface were smaller than those on the (211)A surface. Reflecting these results, Ga adatoms on the (211)A–(001) non-planar surface migrate on the (211)A side surface beyond about 1100K, whereas Ga adatoms mainly diffused across the (001) surface below about 1100K.

An ab initio Based Approach to Ga Adatom Migration on GaAs(n11)A–(001) Non-Planar Surfaces. T.Ito, K.Asano, T.Akiyama, K.Nakamura, K.Shiraishi, A.Taguchi: Applied Surface Science, 2005, 244[1-4], 178-81

Figure 1

Diffusivity of V in GaAs