The adsorption and diffusion behaviour of a Ga adatom on the GaAs (001)c(4 x 4)-heterodimer surface were studied by employing ab initio density functional theory computations in the local density approximation. Structural and bonding features of the c(4 x 4)-heterodimer reconstruction surface were examined. A comparison with the c(4 x 4)-ss reconstruction was performed. Minimum energy sites on the c(4 x 4)-heterodimer surface were located by mapping the potential energy surface for a Ga adatom. Barriers for diffusion of a Ga adatom between the neighbouring minimum energy sites were calculated by using top hopping- and exchange-diffusion mechanisms. Two unique diffusion pathways for a Ga adatom diffusing between the global minima of two neighbouring unit cells were proposed. Signature differences between electronic structures of top hopping- and exchange diffusion mechanisms were studied for relevant atoms. A higher diffusion barrier was observed for exchange mechanism, as compared to top hopping.

Diffusion of a Ga Adatom on the GaAs(001)-c(4 x 4) Heterodimer Surface: a First Principles Study. J.L.Roehl, S.Aravelli, S.V.Khare, R.J.Phaneuf: Surface Science, 2012, 606[15-16], 1303-7