Berlin 2008 – scientific programme
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DS: Fachverband Dünne Schichten
DS 17: Poster: Trends in Ion Beam Technology, Magnetism in Thin Films, Functional Oxides, High-k Dielectric Materials, Semiconductor Nanophotonics, Nanoengineered Thin Films, Layer Deposition Processes, Layer Growth, Layer Properties, Thin Film Characterisation, Metal and Amorphous Layers, Application of Thin Films
DS 17.4: Poster
Tuesday, February 26, 2008, 09:30–13:30, Poster A
Investigation of the system C60/ITO by X-ray absorption and resonant X-ray emission spectroscopy — •Karl Heinz Hallmeier1, Daniel Wett1, Reinhard Denecke1, Iver Lauermann2, Konstantinos Fostiropoulos2, and Boyan Johnev2 — 1Wilhelm-Ostwald-Institut, Universität Leipzig, Linnéstr. 2, D-04103 Leipzig — 2Hahn-Meitner-Institut Berlin GmbH, Dep. SE 2, Glienicker Str. 100, D-14109 Berlin
The system C60/ITO is currently used to develop organic solar cells. In order to characterize this system, X-ray absorption spectroscopy in the total electron yield mode (TEY) and resonant X-ray emission spectroscopy (XES) in dependence of the polarization of the incoming beam have been performed at BESSY II (beamline U41-PGM) using the spectroscopic apparatus ROSA. In the present study we investigated layers of 50 nm C60 on ITO substrates, deposited by vacuum thermal evaporation of commercially available powders from graphite crucibles. While all our resonant (and non-resonant) XES data are identical to the spectra for free C60 powder [1] and also the first four absorption lines in the TEY spectrum agree, distinct differences appear in the high-energy (continuum) region. Possible explanations are electronic interactions resulting in a dipole between the uppermost ITO atoms (preferentially oxygen) and carbon atoms from a C60 molecule, or structural effects resulting from (multiple) backscattering of electrons excited from the carbon 1s level by the uppermost atoms of the ITO substrate. Financial support by DFG (FG 404-SZ58/15).
[1] J. Guo, J. Nordgren, J. Electr. Spectr. Rel. Phen., 110 (2000) 105.