Switching from weakly to strongly limited injection in self-aligned, nano-patterned organic transistors.
Organic thin-film transistors for high frequency applications require large transconductances in combination with minimal parasitic capacitances. Techniques aiming at eliminating parasitic capacitances are prone to produce a mismatch between electrodes, in particular gaps between the gate and the interlayer electrodes. While such mismatches are typically undesirable, we demonstrate that, in fact, device structures with a small single-sided interlayer electrode gap directly probe the detrimental contact resistance arising from the presence of an injection barrier. By employing a self-alignment nanoimprint lithography technique, asymmetric coplanar organic transistors with an intentional gap of varying size (< 0.2 μm) between gate and one interlayer electrode are fabricated. An electrode overlap exceeding 1 μm with the other interlayer has been kept. Gaps, be them source or drain-sided, do not preclude transistor operation. The operation of the device with a source-gate gap reveals a current reduction up to two orders of magnitude compared to a source-sided overlap. Drift-diffusion based simulations reveal that this marked reduction is a consequence of a weakened gate-induced field at the contact which strongly inhibits injection.
Institute of Solid State Physics, Graz University of Technology and NAWI Graz, Petersgasse 16, 8010 Graz, Austria.
Karin
K
Zojer
MATERIALS - Institute for Surface Technologies and Photonics, Joanneum Research Forschungsgesellschaft mbH, Franz-Pichler-Strasse 30, 8160 Weiz, Austria.
Thomas
T
Rothländer
Graz Centre for Electron Microscopy and Institute for Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria.
Johanna
J
Kraxner
Graz Centre for Electron Microscopy and Institute for Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria.
Roland
R
Schmied
MATERIALS - Institute for Surface Technologies and Photonics, Joanneum Research Forschungsgesellschaft mbH, Franz-Pichler-Strasse 30, 8160 Weiz, Austria.
Ursula
U
Palfinger
Graz Centre for Electron Microscopy and Institute for Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria.
Harald
H
Plank
Graz Centre for Electron Microscopy and Institute for Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria.
Werner
W
Grogger
MATERIALS - Institute for Surface Technologies and Photonics, Joanneum Research Forschungsgesellschaft mbH, Franz-Pichler-Strasse 30, 8160 Weiz, Austria.
Anja
A
Haase
MATERIALS - Institute for Surface Technologies and Photonics, Joanneum Research Forschungsgesellschaft mbH, Franz-Pichler-Strasse 30, 8160 Weiz, Austria.
Herbert
H
Gold
MATERIALS - Institute for Surface Technologies and Photonics, Joanneum Research Forschungsgesellschaft mbH, Franz-Pichler-Strasse 30, 8160 Weiz, Austria.
Barbara
B
Stadlober
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