Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 36: Poster Session II (Organic films and electronics, photoorganics; Nanostructures; Plasmonics and nanooptics, Surface chemical reactions and heterogeneous catalysis, Surface dynamics )
O 36.8: Poster
Tuesday, March 12, 2013, 18:15–21:45, Poster B2
Tuning the work function of metal substrates by defined cleaning procedures and self assembling monolyers — •Marc Hänsel1,3, Eric Mankel1,3, Janusz Schinke2,3, Wolfgang Kowalsky2,3, Thomas Meyer1,3, and Wolfram Jaegermann1,3 — 1Technische Universität Darmstadt, Materials Science Institute, Petersenstr. 32, Darmstadt — 2Technische Universität Braunschweig, Institut für Hochfrequenztechnik und Photonik, Schleinitzstr. 22, Braunschweig — 3InnovationLab GmbH, Speyerer Str. 4, Heidelberg
Understanding the contact behavior of organic semiconductors is a prerequisite to improve the efficiency of devices. Self-assembling monolayers (SAMs) are an interesting and promising way to vary and to define the work function of substrate materials. To investigate the influence of the SAMs a reproducible substrate is required. For this 150nm thick gold layers were evaporated on flat silicon substrates. Different treatments (eg. oxygen and argon plasma only and in combination with an ethanol bath, heating under atmosphere and vacuum, UV radiation, argon sputtering) for cleaning were evaluated by photo emission spectroscopy (XPS/UPS). Depending on the procedure different levels of cleanness and work functions between 3.5eV and 5.3eV were achieved. The best reproducible and practical method was argon plasma treatment leading to work functions of 4.8eV and sub monolayer adsorbate concentrations. First experiments are done with selected SAMs like Perfluorodecanethiol. XPS measurements prove a Perfluorodecanethiol layer on the gold surface and Kelvin probe force microscopy shows a work function increase of 1eV compared to an untreated gold sample.