EPITAXIAL CONTINUED-LAYER STRUCTURE OF SB ON GAAS(110) AS OBSERVED BYGRAZING-INCIDENCE X-RAY-DIFFRACTION

The atomic geometry of the Sb/GaAs(110) interface has been determined by means of a grazing-incidence x-ray-diffraction study. The in-plane coordinates of the Sb atoms on GaAs(110) are found in perfect agreemen t with an epitaxial continued-layer structure and exclude an epitaxial on-top structural model. The chains of Sb atoms along the [1 $($) ove r bar$$ 10] direction are characterized by a Sb-Sb bond length of 2.80 Angstrom, close to the covalent Sb-Sb bulk value. The stable (1X1)-Sb /GaAs(110) interface presents a highly ordered structure, with a coher ent domain size of 800 Angstrom, larger than for the clean GaAs surfac e (similar to 600 Angstrom), indicating an ordering role of antimony f or the GaAs(110) surface.