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 Karl Franzens University Graz

Graz University of Technology 

Megahertz Organic Thin-Film Transistors for Flexible Displays
Hagen Klauk
Max Planck Institute for Solid State Research, Stuttgart
17:15 - 18:15 Tuesday 14 March 2017 TUG P2

Organic thin-film transistors (TFTs) can typically be fabricated at temperatures below about 100 °C and thus not only on glass or quartz substrates, like hydrogenated amorphous silicon (a-Si:H) or polycrystalline silicon TFTs, but also on a variety of unconventional substrates, such as plastics and paper. This makes organic TFTs potentially useful for the realization of flexible, large-area electronics applications, such as rollable or foldable information displays and conformable sensor arrays. In advanced applications, such as the integrated row and column drivers of active-matrix flat-panel displays, the TFTs must be able to control electrical signals of a few volts at frequencies of a few megahertz. This can be achieved by aggressively scaling all transistor dimensions, i.e., the gate-dielectric thickness, the channel length, and the parasitic gate-to-contact overlaps. By employing a hybrid gate dielectric with a thickness of about 5 nm and a high-resolution stencil-mask process, organic TFTs with an operating voltage of about 3 V, a channel length as small as 0.5 µm, gate-to-contact overlaps
as small as 2 µm, on/off current ratios up to 10⁶, subthreshold slopes as steep as 95 mV/decade, and signal delays as short as 420 ns for p-channel TFTs and 6.6 µs for n-channel TFTs (measured in 11-stage unipolar and complementary ring oscillators) can thus be fabricated on flexible plastic substrates.