Synchrotron x-ray diffraction studies of metal overlayers on Si(100)

X-ray diffraction is one of the most powerful tools to determnine the atomic structure of surfaces and interfaces. In this paper, after a brief overview of the main features of the technique, we present a summary of our most recent X-rsy diffraction results on the clean Si(100) structure and on the reconstructions induced by the adsorption of Sn and Sb on the same surface. By measuring the scattered intensity along the fractional order rods, we determined the three dimensional structure of the surfaces, together with the induced subsurface silicon lattice relaxation. We characterized the metal deposition process as well, showing that the clean Si(100)-2x1 structure is not destroyed by the Sn and Sb metal deposition at RT. Is is only with the thermal treatment that Si-Si dimers brak apart and the surface orders forming metal-induced reconstructions.