Regensburg 2007 – wissenschaftliches Programm
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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices
SYOE 8: Poster Session SYOE
SYOE 8.20: Poster
Dienstag, 27. März 2007, 18:00–20:00, Poster B
Investigation of the charge carrier injection in pentacene transistors with modified contacts — •Peter Nill1, Norbert Koch2, and Jens Pflaum1 — 1Universität Stuttgart, 3. Phys. Institut, 70550 Stuttgart, Germany — 2HU Berlin, Institut für Physik, 12489 Berlin, Germany
A crucial aspect concerning the performance of thin-film field-effect transistors (TFTs) is the charge carrier injection across the interface between the metal contacts and the molecular layer. Recently, we [1] pointed out that the position of electronic states contributing to charge injection depends on the respective molecular orientation as well as on possible molecular overlayers on the metal surface. Based on this observation we present our current investigation on the possibility to exploit this effect in order to alter the injection characteristics in pentacene-based TFTs with bottom-contact geometry. In our approach, we prepare by thermal treatment an additional molecular monolayer on top of the Au contacts, whereas the SiO2 channel region remains uncovered. A 30nm thick pentacene film is then thermally deposited onto this structure as the TFT’s active transport layer. Electronic characterisation reveals a significant enhancement of the saturation current by up to one order of magnitude for TFTs with modified versus those with un-modified metal contacts. As the measured hole mobility remains the same for both transistor structures we will discuss the observation of an enhanced saturation current in the context of an effective lowering of the contact resistance.
[1] N. Koch, et al., Organic Electronics 7 (2006) 537.