Matched printed carbon nanotube complementary metal-oxide-semiconductor (CMOS) devices for flexible circuits

The development of matched carbon nanotube (CNT) complementary metal-oxide-semiconductor (CMOS) devices still remains a challenge for flexible and low-power-dissipation circuits. In this study, we found a reliable technique to achieve matched CNT CMOS thin-film transistors (TFTs) for integrated circuits (IC) with low power consumption. The enhancement-mode p-type CNT TFTs were obtained using the low-work-function Al gate electrodes and ultrathin (10 nm) Al2O3 dielectrics, which exhibit the average field-effect mobility(μ) of 6.5 cm2V−1s−1, subthreshold swing (SS) down to 70–85 mV/dec and on/off ratio up to 106 at the low working voltages between −1.5 V and 0.5 V, as well the outstanding stability and mechanical flexibility after 10,000 cycles of bending. Then, by adjusting the aspect ratios of the TFT channels and selectively dropping the electron-doping inks into p-type CNT TFTs’ channels, matched n-type and p-type CNT TFTs were obtained. Finally, flexible printed CMOS inverters with high noise tolerance (84% of 1/2 VDD), high voltage gain (over 32), and low power consumption (down to 32.9 pW) were successfully constructed, owing to the work style of CMOS circuits and electrically symmetrical n-type and p-type TFTs. Furthermore, good-performance NAND and NOR gates have been demonstrated. This work can effectively resolve the leakage current issue of flexible carbon-based electronics with the ultra-thin dielectrics by optimizing the conductive ink formula and printing technology.