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O: Fachverband Oberflächenphysik
O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)
O 36.93: Poster
Dienstag, 15. März 2011, 18:30–22:00, P4
The Formation of Shockley derived Interface States at Metal-Organic Interfaces studied with 2PPE — •Manuel Marks1, Christian H. Schwalb1, Sönke Sachs2, Benjamin Schmidt1, Achim Schöll2, Friedrich Reinert2, Eberhard Umbach2, and Ulrich Höfer1 — 1Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität Marburg, D-35032 Marburg — 2Universität Würzburg, Experimentelle Physik II, D-97074 Würzburg
The charge carrier injection across a metal-organic
interface into the active regions of a functional device is one
major influence on the efficiency of organic electronics. New
electronic states that emerge at such interfaces can alter these
dynamical processes substantially. We applied time- and
angle-resolved 2-photon photoemission (2PPE) to study the electron
dynamics at structurally well characterized interfaces directly in
the time domain. With adsorption of monolayer films of PTCDA and
NTCDA on a Ag(111) surface strongly dispersing interface states (IS)
form above the Fermi Level EF. For PTCDA the inelastic
electron lifetime of 54 fs indicates a significant overlap with the
metal substrate and the state mainly originates from an upshifted
Shockley state [1]. For NTCDA films the IS has comparable properties
though lying closer to EF. In the stronger chemisorbed
disordered precursor phase of the PTCDA monolayer [2] an interface
state emerges at E−EF=0.45 eV. The lifetime of 63 fs and
its non-dispersing behavior raise the question
whether this state has more molecular character.
[1] C. H. Schwalb et al., Phys. Rev. Lett. 101, 146801 (2008)
[2] L. Kilian et al., Phys. Rev. Lett. 100,
136103 (2008)