Resonant-photoemission study of the mechanism for room-temperature-alloyed interface formation of Au and Ag on Si(111)-(2×1)

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Abstract
Room-temperature deposition of gold and silver on the Si(111)-(2×1) surface was studied by photoemission spectroscopy. We successfully observed, around the photon energy of the Si(2p) core excitation threshold (∼100 eV), a resonancelike enhancement of the photoemission signal of Au(5d) at around monolayer coverage of Au, while no enhancement of the Ag(4d) signal was observed at around monolayer coverage of Ag. This result indicates the formation of a covalentlike bond between Au (deposited) and Si (substrate) atoms and not in Ag-Si, and the mechanism of room-temperature-alloyed interface formation at a metal-semiconductor interface can be described by the ‘‘chemical-bonding model’’ proposed before by the authors [M. Iwami, T. Terada, M. Kubota, H. Tochihara, and Y. Murata, Surf. Sci. 119, 115 (1988)].