Scalable Preparation of High-Density Semiconducting Carbon Nanotube Arrays for High-Performance Field-Effect...

Although chemical vapor deposition (CVD)-grown carbon nanotube (CNT) arrays are considered ideal materials for constructing high-performance field-effect transistors (FETs) and integrated circuits (ICs), a significant gap remains between the required and achieved densities and purities of CNT arrays. Here, we develop a directional shrinking transfer method to realize up to 10-fold density amplification of CNT array films without introducing detectable damage or defects. In addition, the method improves the film uniformity while retaining the perfect alignment and high carrier mobility of 1600 cm² V^-1 s^-1 of CVD-grown CNT arrays. By combining the density amplification method with the thermocapillary flow method developed by Rogers et al., semiconducting CNT arrays with high densities and high qualities are obtained. High-performance FETs with a channel length of 200 nm are demonstrated using these high-density semiconducting CNT arrays, yielding a record-high on-state current density of 150 μA/μm, a peak transconductance of 80 μS/μm, and a current on/off ratio of more than 10⁴ among the CVD-grown CNT-based FETs.