X-ray standing-wave study of an Sb-terminated GaAs(001)-(2×4) surface

Abstract

The Sb-Sb dimer structure of a 2\ifmmode\times\else\texttimes\fi{}4 reconstructed Sb/GaAs(001) surface was investigated by core-level photoelectron collection mode of back reflection soft x-ray standing-wave technique. Sb atoms occupy the bridge site forming bonds with two underlying Ga atoms and form symmetric Sb-Sb dimers lining up in the [11\ifmmode\bar\else\textasciimacron\fi{}0] direction. The first-layer Sb atomic plane is estimated to be 1.81\ifmmode\pm\else\textpm\fi{}0.02 \AA{} above the second-layer Ga lattice plane. The bond length of the Sb-Sb dimer on a GaAs(001) surface is estimated to be 2.95\ifmmode\pm\else\textpm\fi{}0.06 \AA{}, which is longer than the reported Sb-Sb bond length for Sb/GaAs(110) surface.