Recent Progress in Obtaining Semiconducting Single‐Walled Carbon Nanotubes for Transistor Applications

High purity semiconducting single‐walled carbon nanotubes (s‐SWCNTs) with a narrow diameter distribution are required for high‐performance transistors. Achieving this goal is extremely challenging because the as‐grown material contains mixtures of s‐SWCNTs and metallic‐ (m‐) SWCNTs with wide diameter distributions, typically inadequate for integrated circuits. Since 2000, numerous ex situ methods have been proposed to improve the purity of the s‐SWCNTs. The majority of these techniques fail to maintain the quality and integrity of the s‐SWCNTs with a few notable exceptions. Here, the progress in realizing high purity s‐SWCNTs in as‐grown and post‐processed materials is highlighted. A comparison of transistor parameters (such as on/off ratio and field‐effect mobility) obtained from test structures establishes the effectiveness of various methods and suggests opportunities for future improvements.