High-gain, low-voltage unipolar logic circuits based on nanoscale flexible organic thin-film transistors with small signal delays
Tanumita Haldar, Tobias Wollandt, J. Weis, Ute Zschieschang, Hagen Klauk, R. Thomas Weitz, Joachim N. Burghartz, Michael Geiger
Abstract
One of the circuit topologies for the implementation of unipolar integrated circuits (circuits that use either p-channel or n-channel transistors, but not both) is the zero- V GS architecture. Zero- V GS circuits often provide excellent static performance (large small-signal gain and large noise margins), but they suffer from the large signal delay imposed by the load transistor. To address this limitation, we have used electron-beam lithography to fabricate zero- V GS circuits based on organic transistors with channel lengths as small as 120 nm on flexible polymeric substrates. For a supply voltage of 3 V, these circuits have characteristic signal-delay time constants of 14 ns for the low-to-high transition and 560 ns for the high-to-low transition of the circuit’s output voltage. These signal delays represent the best dynamic performance reported to date for organic transistor–based zero- V GS circuits. The signal-delay time constant of 14 ns is also the smallest signal delay reported to date for flexible organic transistors.