Diameter-Dependent Semiconducting Carbon Nanotube Network Transistor Performance

Single-walled carbon nanotube (SWCNT) network based devices show application potentials due to their extraordinary electric and optical properties, and the device performance is largely determined by the network morphology and tube-tube junction interactions. In this work, five SWCNT samples with narrow bandgap distributions covering a wide diameter range of 0.7-1.6 nm were purified by the conjugated polymer extraction (CPE) process. Both chirality distribution and semiconducting purity of these samples were systematically characterized by optical methods. Uniform high density network based thin film transistors (TFTs) were fabricated, and their performance can be related to tube bandgap/diameter and defects density or tube length. The diameter-dependent tube-tube junction resistance, the most important parameter for nanowire network devices, was extracted using a network predictive model. It was found that junction resistance inversely scales with tube diameter and is about 2 orders of magnitude higher than tube intrinsic resistance. The impacts of network morphology, tube diameter, and length on their network TFT performance were further discussed. We hope these results can provide some guideline to address various application challenges for SWCNT network based devices.