Berlin 2008 – scientific programme

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DS: Fachverband Dünne Schichten

DS 18: Poster: Towards Molecular Spintronics, Organic Thin Films, Optical Layers, Vibrational Spectroscopy, Tayloring organic interfaces

DS 18.23: Poster

Tuesday, February 26, 2008, 14:30–19:30, Poster A

Investigation of thermally activated charge carrier transport in thin perylene layers — •Moritz Schaefer, Christian Effertz, Maryam Beigmohamadi, Phenwisa Niyamakom, Azadeh Farahzadi, Philip Schulz, and Matthias Wuttig — Institute of Physics (IA), RWTH Aachen University, 52056 Aachen, Germany

The production of organic thin-film transistors (OTFTs) is a low cost process. Therefore, they are promising for large area TFT arrays as needed in low cost electronic paper, RFID tags, etc. [1]. Recently reported characteristics of OTFTs in terms of mobility and Ion/Ioff-ratio are similar to those of the currently used hydrogenated amorphous silicon (a-Si:H) TFTs [1]. It is now possible to produce OTFTs with a comparable high performance, but the transport phenomena in the organic layer are still not completely understood.

We present the electronic characteristics of perylene based OTFTs. Transfer and output characteristics were measured in order to determine the mobility μ(T) and the threshold voltage VT(T). For this purpose, a stage was designed that can be cooled to -50°C and heat to +100°C. The active layer of the transistors was produced by vacuum thermal evaporation (VTE) via a temperature controlled substrate holder with a temperature range from -40°C to +35°C. The organic film thickness was varied between 25 nm and 500 nm. Atomic Force Microscopy (AFM) and x-ray diffraction (XRD) have been used in order to determine the crystallinity and morphology of the organic layer.

[1] D. S. Park, et. al., J. Vac. Sci. Technol. B 23(3) (2005)