Dr Hagen Klauk

Hagen Klauk
Max Planck Institute

Biography

Hagen Klauk received his PhD in electrical engineering from the Pennsylvania State University in 1999. From 2000 to 2005 he was with the Polymer Electronics Group at Infineon Technologies in Erlangen. Since August 2005 he has been head of the Organic Electronics group at the Max Planck Institute for Solid State Research in Stuttgart, Germany.

About the Organic Electronics Research Group at Max Planck

The Max Planck Research Group (formerly "Independent Junior Research Group") at the Max Planck Institute for Solid State Research in Stuttgart was established in August 2005.

Research focuses on novel functional organic materials and on the manufacturing and characterization of organic and nanoscale electronic devices, such as high-performance organic thin-film transistors, carbon nanotube field-effect transistors, inorganic semiconductor nanowire field-effect transistors, and organic/inorganic hybrid radial superlattices.

Of particular interest is the use of molecular self-assembled monolayers in functional electronic devices. We are developing materials and manufacturing techniques that allow the use of high-quality self-assembled monolayers as the gate dielectric in low-voltage organic and inorganic field-effect transistors and low-power integrated circuits on flexible substrates. We are also studying the use of self-assembled monolayers for the preparation of nano-scale organic/inorganic superlattices that exhibit unique electrical, optical, and mechanical properties.

Scientific work in organic electronics is highly interdisciplinary and involves the design, synthesis and processing of functional organic and inorganic materials, the development of advanced micro- and nanofabrication techniques, device and circuit design, and materials and device characterisation.

Abstract

Megahertz Flexible Low-Voltage Organic Thin-Film Transistors

Organic thin-film transistors (TFTs) can typically be fabricated at temperatures of about 100 ºC or less and thus not only on glass or polyimide substrates, but also on inexpensive and optically transparent types of plastics, such as polyethylene naphthalate (PEN), and even on paper. In some of the more advanced applications for organic TFTs, such as the integrated row and column drivers of active-matrix flat-panel displays or image sensors, the TFTs may need to be able to control electrical signals of a few volts at frequencies of a few megahertz. This can be achieved by aggressively reducing all transistor dimensions, i.e., the channel length, the parasitic gate-to-source and gate-to-drain overlaps, and the gate-dielectric thickness. For this purpose, we have developed a process in which the TFTs are patterned using high-resolution silicon stencil masks and in which a 5-nm-thick hybrid gate dielectric is employed. With this process, bottom-gate, top-contact organic TFTs with channel lengths as small as 0.5 µm and gate-to-contact overlaps as small as 5 µm can be fabricated on flexible PEN substrates. Owing to small thickness of the gate dielectric, the TFTs can be operated with voltages of about 2 to 3 V. For 11-stage unipolar and complementary ring oscillators based on TFTs with a channel length of 1 µm and a gate overlap of 5 µm, we have measured signal propagation delays per stage as short as 420 ns and 6.6 µs, respectively, both at a supply voltage of 3 V.

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