Dresden 2006 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 23: POSTER Functional Organic Thin Films
CPP 23.22: Poster
Donnerstag, 30. März 2006, 17:00–19:00, P2
Encapsulated organic thin film transistors at elevated temperatures — •S. Meyer1, J. Pflaum1, S. Sellner2, G. Ulbricht2, F. Schreiber3, H. Dosch2, M. Fischer4, and B. Gompf4 — 1III. Physikalisches Institut, Universität Stuttgart — 2Max-Planck-Institut für Metallforschung, Stuttgart — 3Institut für Angewandte Physik, Universität Tübingen — 4I. Physikalisches Institut, Universität Stuttgart
To address the problem of thermal stability of organic semiconducting layers under realistic device conditions we have performed studies on pentacene thin film transistors with and without encapsulation. The capping is realized by a 2 µ m polymer layer of poly-para-xylylene (PPX) or, alternatively, by a 100 nm thick sputtering layer of aluminum oxide (AlOx.). On capped pentacene TFTs a field-effect can be demonstrated for both encapsulations up to temperatures of 140∘C which is about 40∘C above the desorption point of uncapped pentacene films on SiO2. From the TFT characteristics a complex behavior of the temperature dependent hole mobility can be deduced, indicating that the device operation at these elevated temperatures is predominantly limited by the transistor structure and not by the organic material itself.
This is confirmed by thermal desorption spectroscopy and X-ray diffraction studies on pentacene thin films, showing that the organic layer remains crystalline for both capping materials far above the breakdown temperature of the TFTs. As was previously demonstrated for AlOx.-capped diindenoperylene thin films [1], the structural breakdown is a function of heating rate and thickness of the capping layer.
Sellner et al., Adv. Mat. 16, 1750 (2004)