Determination of the bonding and growth of Ag on Si(100)-(2×1)

The bonding and growth of Ag on Si(100) were studied with high-resolution photoemission spectroscopy and high-energy electron diffraction. By monitoring the changes in the Si 2p core-level and Ag 4d valence-band line shapes, we have examined the chemical interaction between the Ag adatoms and Si surface dimer atoms. The Ag-to-Si bonding coordination number as a function of coverage was obtained. This number is 2 at low Ag coverages, which suggests that the bonding site for a Ag adatom is between two neighboring Si surface dimers along the direction of dimerization; the two dimer dangling bonds pointing at the Ag adatom join the two Ag sp hybrid orbitals to form two Ag-Si bonds. The growth mode was observed to be three dimensional at higher coverages. The Schottky-barrier height was measured.