Structure of the sulfur-passivated GaAs(001) surface

Abstract

The adsorption position of sulfur atoms in the sulfur-passivated GaAs(001) surface is investigated by soft-x-ray standing-wave triangulation using two types of noncentrosymmetric (11\ifmmode\bar\else\textasciimacron\fi{}1) and (111) diffraction planes inclined by 54\ifmmode^\circ\else\textdegree\fi{} to the (001) surface. The sulfur atoms are at the bridge site on the Ga-terminated GaAs(001) surface, forming bonds with the underlying Ga atoms. The sulfur atomic layer is approximately 1.1 \AA{} above the underlying Ga atomic layer. The existence of symmetric sulfur-sulfur dimers lining up in the [11\ifmmode\bar\else\textasciimacron\fi{}0] direction is not confirmed for the 2\ifmmode\times\else\texttimes\fi{}1 reconstructed S/GaAs(001) surface.