Submicron low-voltage organic transistors and circuits enabled by high-resolution silicon stencil masks

Using high-resolution silicon stencil masks and employing a resist-free, solvent-free, low-temperature (90°C) fabrication process we have fabricated low-voltage top-contact organic thin-film transistors (TFTs) with a channel length down to 0.8 μm. To observe the scaling requirements and to alleviate short-channel effects, a thin gate dielectric with a thickness of 5.3 nm is employed. The p-channel TFTs have a record static performance, with a transconductance of 1 S/m, an on/off current ratio of 10⁸, and a subthreshold swing of 100 mV/dec. Unipolar inverters based on p-channel TFTs with a channel length of 1 μm and gate-to-source and gate-to-drain overlaps of 2 μm respond to input signals with frequencies up to 1 MHz. Combining air-stable p-channel and n-channel TFTs we have also realized organic complementary ring oscillators with record low-voltage dynamic performance (signal delay of 30 μs per stage at a supply voltage of 3 V).