Dual threshold voltage integrated organic technology for ultralow-power circuits

For the first time, we demonstrate control of organic thinfilm transistor's (OTFT) threshold voltage (V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> ) by modifying the gate work function. We present a near-room-temperature, fully lithographic process to fabricate integrated pentacene dual V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> OTFTs suitable for large-area and flexible mixed signal circuits. Platinum and aluminum are used as the gate metals for the high V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> (more depletion-like) and low V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> (more enhancement-like) p-channel devices, respectively. The availability of a high V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> device enables area-efficient zero-VGS current source loads. We demonstrate positive noise margin inverters which use pico Watts of power and a 3 V supply. Compared to a single V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> implementation, the dual V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> inverter occupies an area that is 30x smaller, and is 17x faster. These results show that p-channel only organic technologies can produce functional and low-power circuits without integrating a complementary device.