Surface structure of bismuth terminated GaAs surfaces grown with molecular beam epitaxy

We determine the atomic surface structure of the Bi-terminated GaAs(001) (1 × 3) reconstruction for the first time using scanning probe microscopies, photoemission spectroscopy, and ab initio calculations. The proposed kinked-dimer (4 × 3) model is consistent with experimental characterization and can accommodate a variety of species configurations due to an availability of low-energy sites for Bi substitution, accounting for the significant observed local disorder. In addition, experiments show that stability of this reconstruction coincides with a dramatic change in surface step morphology, giving rise to strong up/down step interaction and a counterintuitive smoothing effect on the micrometer length scale.