Moderate-Temperature Deposition of 99.9% Semiconducting Carbon Nanotubes for Thin Film Transistors With Good Consistency

Carbon nanotube (CNT) networks are considered as promising candidate materials for high-performance thin film transistors. However, the complex network structure usually leads to device-to-device variations among the fabricated CNT field-effect transistors (CNTFETs), and thus impeding their practical applications. In this work, we report the solution-based deposition of CNT networks at a moderate temperature of 60 °C by using high-purity (99.9%) semiconducting nanotubes, which not only improves the deposition efficiency, but also produces well-controlled network morphology. The resultant CNTFETs exhibit narrow distributions in on/off ratios and subthreshold swings centered at 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> and 2 V/dec (with a 300 nm-thick silicon oxide dielectric layer), respectively, with a mobility of ~20 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs. The device performance can be further optimized by using a plasma-generated ultra-thin aluminum oxide gate dielectric layer. In particular, this work underlines the importance of controlling the nanotube bundles in high-purity semiconducting CNT networks, by which the trade-off between carrier mobility and on/off ratio of CNTFETs can be well balanced.