Dresden 2009 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 22: Organic Thin Films II
DS 22.7: Vortrag
Mittwoch, 25. März 2009, 12:45–13:00, GER 38
Chemical and electronic properties of the In-on-CuPc contact: a photoemission study — •Teodor Toader1, Jan Ivanco1, Alexander Firsov2, Walter Braun2, and D.R.T. Zahn1 — 1Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany — 2BESSY GmbH, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
The interfacial chemistry and the evolution of electronic structure was studied during the formation of a top indium contact on CuPc in ultra-high vacuum. The In 4d core level revealed two components: the metallic component and a second one shifted towards higher binding energy. In recent studies, such a shifted component was associated with the formation of a reactive In/CuPc interface. The appearance of so-called gap states near the Fermi level would also provide an argument in favor of a reactive interface. However, probing the interface at different photon energies revealed that the origin of the shifted component is located at the surface of In rather than buried at the In/CuPc interface, as one would expect for reactive components. Given also the fact that the other core levels C 1s and N 1s indicated no reaction between In and CuPc, we assume that both the shifted component in the In 4d core level and the gap states are due to final state effects and/or charging related to the formation of metallic nanoclusters instead of a continuous metallic film. The presence of indium nanoclusters on the CuPc surface is corroborated by the secondary electron microscopy (SEM).