Exploring the Performance Limit of Carbon Nanotube Network Film Field‐Effect Transistors for Digital Integrated Circuit Applications

Abstract

AbstractCarbon nanotube (CNT) network thin film field‐effect transistors (TFTs), which used to be considered as low cost and low performance transistors for display driving or flexible electronics, have recently been used to construct digital integrated circuits (ICs). However, few studies have focused on exploring how optimal CNT TFTs can be achieved according to transistor standards in digital applications. In this work, sub‐micrometer TFTs based on high‐quality and high‐purity solution‐derived CNT films are fabricated and the potential performance restriction due to the switching‐off property of these transistors is explored. Specifically, subthreshold swing (SS) severely degrades upon scaling down the channel length or increasing the CNT density in TFTs, and a tradeoff between peak transconductance (gm) and SS in CNT TFTs due to the random orientation distribution of CNTs has been observed in experiments and proven by theoretical simulations. A well‐designed balance between gm and SS is necessary to build CNT TFTs with SS of 120 mV dec−1 and gm of 150 µS µm−1 to meet device requirements in digital ICs powered by a supplied voltage, VDD, lower than 2.0 V.