title: The paradox of an insulating contact between a chemisorbed molecule and a wide band gap semiconductor surface.
abstract: Controlling the intrinsic optical and electronic properties of a single molecule adsorbed on a surface requires electronic decoupling of some molecular orbitals from the surface states. Scanning tunneling microscopy experiments and density functional theory calculations are used to study a perylene molecule derivative (DHH-PTCDI), adsorbed on the clean 3 × 3 reconstructed wide band gap silicon carbide surface (SiC(0001)-3 × 3). We find that the LUMO of the adsorbed molecule is invisible in I(V) spectra due to the absence of any surface or bulk states and that the HOMO has a very low saturation current in I(z) spectra. These results present a paradox that the molecular orbitals are electronically isolated from the surface of the wide band gap semiconductor even though strong chemical bonds are formed.
authors.affiliation: Institut des Sciences Moléculaires d'Orsay, CNRS, Université Paris Sud 11, 91405 Orsay, France.
authors.forename: H
authors.initials: H
authors.lastname: Yang
authors.forename: O
authors.initials: O
authors.lastname: Boudrioua
authors.forename: A J
authors.initials: AJ
authors.lastname: Mayne
authors.forename: G
authors.initials: G
authors.lastname: Comtet
authors.forename: G
authors.initials: G
authors.lastname: Dujardin
authors.forename: Y
authors.initials: Y
authors.lastname: Kuk
authors.forename: Ph
authors.initials: P
authors.lastname: Sonnet
authors.forename: L
authors.initials: L
authors.lastname: Stauffer
authors.forename: S
authors.initials: S
authors.lastname: Nagarajan
authors.forename: A
authors.initials: A
authors.lastname: Gourdon