Fermi-level pinning of Ag on Si(111)-(7x7)

Abstract

The electronic structure of the Ag overlayer reconstructed on Si(111) has been studied by using ultraviolet photoemission spectroscopy with synchrotron radiation. Strong Fermi-level pinning observed in Si(111)-(root 3 X root 3)R30 degrees-Ag reconstructed phases is decreased in the (3 X 1) phase, where the pinning level is quite comparable to that of thick layers. The position and width of the Ag 4d band are invariant under this phase change. These results raise strong questions on the origin of Fermi-level pinning at this surface. The possible origin of this Fermi-level pinning will be discussed.