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

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)2×1-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±0.03 Å. Each Sb atom of the dimer is bonded to two Si atoms with a Sb-Si bond length of 2.63±0.04 Å. 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.