Polarity tuning of carbon nanotube transistors by chemical doping for printed flexible complementary metal-oxide semiconductor (CMOS)-like inverters

Abstract

Low operation voltages and strong noise immunity are crucial for low-power applications in portable or remote devices. In this work, we present a simple and effective approach to achieve low-voltage and high noise margin complementary metal-oxide semiconductor (CMOS)-like inverters using printed symmetric ambipolar single-walled carbon nanotubes (SWCNT) TFTs on flexible substrates. An ion gel dielectric material with high capacitance is used to achieve small hysteresis and small subthreshold swing at low operation voltages. The printed SWCNT TFTs exhibit a p-type depletion-mode behavior and can be converted into symmetric ambipolar TFTs by chemical doping of triethanolamine into the ion gel inks. The CMOS-like inverters consisting of two ambipolar TFTs exhibit a large noise margin of 72% and 83% at 1/2 VDD = 0.5 V, voltage gain as high as 23 and power consumption of 0.9 μW at VDD = 0.5 V. To our knowledge, they are the best reported values of printed CMOS-like inverter using ion gels as dielectric material at a VDD of 0.5 V. Additionally, the flexible printed CMOS-like inverters consisting of a p-type and an ambipolar TFTs also work well and showed full rail-to-rail output voltage swing and low power consumption (0.3 μW at VDD = 0.75 V).