Surface extended-x-ray-absorption fine structure and scanning tunneling microscopy of Si(001)2×1-Sb

Abstract

Surface extended x-ray-absorption fine structure (SEXAFS) has been combined with scanning tunneling microscopy (STM) to determine both the local and long-range bonding properties of the Si(001)2\ifmmode\times\else\texttimes\fi{}1-Sb interface. Sb ${\mathit{L}}_{3}$ edge SEXAFS shows that Sb dimers occupy a modified bridge site on the Si(001) surface with a Sb-Sb near-neighbor distance of 2.88\ifmmode\pm\else\textpm\fi{}0.03 \AA{}. Each Sb atom of the dimer is bonded to two Si atoms with a Sb-Si bond length of 2.63\ifmmode\pm\else\textpm\fi{}0.04 \AA{}. STM resolves the dimer structure and provides the long-range periodicity of the surface. Low-energy-electron diffraction of vicinal Si(001) shows that the Sb dimer chains run perpendicular to the original Si dimer chains.