29 research outputs found
Metal-Induced Gap States at Well Defined Alkali-Halide/Metal Interfaces
In order to search for states specific to insulator/metal interfaces, we have
studied epitaxially grown interfaces with element-selective near edge X-ray
absorption fine structure (NEXAFS). An extra peak is observed below the bulk
edge onset for LiCl films on Cu and Ag substrates. The nature of chemical bonds
as probed by X-ray photoemission spectroscopy and Auger electron spectroscopy
remains unchanged, so we regard this as evidence for metal-induced gap
states(MIGS) formed by the proximity to a metal, rather than local bonds at the
interface. The dependence on the film thickness shows that the MIGS are as thin
as one monolayer. An ab initio electronic structure calculation supports the
existence of the MIGS that are strongly localized at the interface.Comment: 4 pages, 5 figures, to be published in Phys. Rev. Let
Atomic and Electronic Structures of Unreconstructed Polar MgO(111) Thin Film on Ag(111)
Atomic and electronic structures of a polar surface of MgO formed on Ag(111)
was investigated by using reflection high energy electron diffraction (RHEED),
Auger electron spectroscopy, electron energy loss spectroscopy (EELS), and
ultraviolet photoemission spectroscopy (UPS). A rather flat unreconstructed
polar MgO(111) 11 surface could be grown by alternate adsorption of Mg
and O on Ag(111). The stability of the MgO(111) surface was discussed in
terms of interaction between Ag and Mg atoms at the interface, and charge state
of the surface atoms. EELS of this surface did not show a band gap region, and
finite density of states appeared at the Fermi level in UPS. These results
suggest that a polar MgO(111) surface was not an insulating surface but a
semiconducting or metallic surface.Comment: 6 figures, to be published in Phys. Rev.