Carbon nanotube network film-based ring oscillators with sub 10-ns propagation time and their applications in radio-frequency signal transmission

We have fabricated top-gated ambipolar field-effect transistors (FETs) based on solution-derived carbon nanotube (CNT) network films, and then constructed inverters and ring oscillators (ROs) that can work under supply voltages as low as 0.2 V owing to the high uniformity of the devices. Significant improvements were achieved in the performance of these CNT-based ambipolar FETs and CMOS-like circuits by scaling down the gate length of the CNT FETs and optimizing the device structure and RO layout. In particular, the optimized five-stage RO is shown to present a record high oscillation frequency of up to 17.4 MHz with a propagation time of 5.6 ns at a 12-V working voltage. The CNT film-based ROs were used as carrier-wave generators in radio-frequency systems to demonstrate a complete signal transmission process. These results suggest that CNT thin film-based FETs and integrated circuits may soon find their way to radio-frequency applications with a frequency band of 13.56 MHz.