Regensburg 2007 – scientific programme
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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices
SYOE 8: Poster Session SYOE
SYOE 8.87: Poster
Tuesday, March 27, 2007, 18:00–20:00, Poster B
Nanoscale Organic Field-effect Transistors based on P3HT with switching frequencies above one Megahertz — •Arne Hoppe1, Paul Wöbkenberg2, Jörg Seekamp1, and Veit Wagner1 — 1School of Engineering and Science, International University Bremen, Campus Ring 8, 28759 Bremen, Germany — 2present address: Imperial College London, UK
Switching speed is crucial for many applications in organic electronics. Therefore the improvement of the dynamic properties of organic field effect transistors (OFETs) is a mayor demand. The possibility to achieve higher frequency regimes will enable new fields of applications. We demonstrate high frequency organic thin film transistors based on high-mobility regioregular poly(3-hexylthiophene) (r,r*-P3HT) as active material and silicon oxide as gate dielectric. Transistors built by e-beam lithography with sub-micron channel lengths and gold contacts in bottom configuration show unity-gain bandwidth beyond 1 MHz in air at low supply voltages of 10 V. For channel lengths L below 500 nm deviations from ideal L scaling law are observed experimentally, which are attributed to contact effects. We present a model beyond the ideal scaling law to predict the maximum operational frequency which is based on transistor parameters, geometry and contact resistance. Further deviations of measured transfer frequencies with respect to the expected values are discussed in terms of the organic material properties and interfaces to the gate isolator and electrodes.