Binding and migration paths of Au adatoms on the GaAs(001) surface - art. no. 045308

摘要

The binding and the migration paths of an isolated Au adatom on the GaAs (001)-beta2(2x4) reconstructed surface have been investigated by first-principle total-energy calculation,, in tile Car-Parrinello scheme. The potential energy surface calculated tor the An adatom shows that tile most interesting Au binding Sites are located at short-bridge sites next the As-As dimers of the surface. Similar binding sites were found for Ga adatoms on the same surface. However. the Au chemical binding is different from that of Ga. A Ga adatom forms strong covalent Ga-As bonds with a marked ionic character when interacting With tile As dimers. while the Au-dimer interaction is characterized by the formation of weaker pure covalent Au-As bonds. Accordingly, Au adatoms do not break the As-As dimers at variance with the case of Ga adatoms. The characteristics of tile Au binding also account for an anisotropic An migration that results to be faster along the dimer rows than perpendicular to them. [References: 32]