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 8.85: Poster
Tuesday, March 27, 2007, 18:00–20:00, Poster B
Influence of contact effects on the performance of printed pentacene Thin Film Transistors — •Amare Benor and Dietmar Knipp — International University Bremen, School of Engineering and Science, 28759 Bremen, Germany
Micro Contact Printing (µCP) of self-assembled monolayer (SAMs) in combination with selective surface wetting was used to realize pentacene thin film transistors (TFTs). The combination of µCP and selective wetting/dewetting provides a universal route to pattern a variety of different materials including polymers and metal films. In our study we used the SAMs of octadecyltrichlorosilane (OTS), CH3(CH2)17SiCl3, which was printed on cleaned silicon or glass substrate. The printed monolayer leads to the formation of hydrophilic and hydrophobic regions, which facilitates the selective deposition of polymers or resists like Poly (methyl methacrylate), PMMA, on the hydrophilic regions. Following the selective deposition of a resist, a lift-off process was used to pattern gold and titanium metal thin films. This technique was applied to realize radio frequency (RF) coils and electrodes for pentacene TFTs. The techniques allows for patterning of electrodes down to 2µm. Transistors fabricated by this approach exhibit charge carrier mobilities of 0.2-0.4 cm2/Vs and on/off ratios of 106. The influence of the printed process on contact resistance of the TFTs, charge carrier mobility and the threshold voltage will be discussed. Finally, the electrical characteristic of pentacene TFTs prepared by printing will be compared with transistors prepared by conventional optical lithography.