title: Interaction of epitaxial silicene with overlayers formed by exposure to Al atoms and O2 molecules.
abstract: As silicene is not chemically inert, the study and exploitation of its electronic properties outside of ultrahigh vacuum environments require the use of insulating capping layers. In order to understand if aluminum oxide might be a suitable encapsulation material, we used high-resolution synchrotron photoelectron spectroscopy to study the interactions of Al atoms and O2 molecules, as well as the combination of both, with epitaxial silicene on thin ZrB2(0001) films grown on Si(111). The deposition of Al atoms onto silicene, up to the coverage of about 0.4 Al per Si atoms, has little effect on the chemical state of the Si atoms. The silicene-terminated surface is also hardly affected by exposure to O2 gas, up to a dose of 4500 L. In contrast, when Al-covered silicene is exposed to the same dose, a large fraction of the Si atoms becomes oxidized. This is attributed to dissociative chemisorption of O2 molecules by Al atoms at the surface, producing reactive atomic oxygen species that cause the oxidation. It is concluded that aluminum oxide overlayers prepared in this fashion are not suitable for encapsulation since they do not prevent but actually enhance the degradation of silicene.
authors.affiliation: Japan Advanced Institute of Science and Technology, School of Materials Science, Nomi, Ishikawa 923-1292, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Friedlein
authors.affiliation: MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Van Bui
authors.affiliation: MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands.
authors.forename: F B
authors.initials: FB
authors.lastname: Wiggers
authors.affiliation: Japan Advanced Institute of Science and Technology, School of Materials Science, Nomi, Ishikawa 923-1292, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yamada-Takamura
authors.affiliation: MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands.
authors.forename: A Y
authors.initials: AY
authors.lastname: Kovalgin
authors.affiliation: MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands.
authors.forename: M P
authors.initials: MP
authors.lastname: de Jong