A Review of CNTFETs: Mechanisms, Manufacturing, and Why They Are a Promising Alternative to Silicon MOSFETs

Due to the approaching physical limit of MOSFET scaling resulting from factors including short-channel effect in this post-Moore era, new forms of transistors that exhibit different mechanisms of operation from traditional silicon MOSFETs are gaining increasing attention in research and industry. Among them, the Carbon Nanotube Field-Effect Transistors (CNTFETs), devices that use a Carbon Nanotube as the channel between source and drain, are commonly viewed as promising alternatives. The most common type of Carbon Nanotube used, and the focus of this review, is Single-Walled Carbon Nanotubes (SWCNTs) formed from graphene sheets that are rolled into a cylindrical shape. This manuscript will first cover the basic structure and mechanism of the SWCNTs and CNTFETs – focusing on how CNT's thin channel can potentially mitigate challenges in scaling by minimizing the short-channel effect of silicon MOSFETs, while maintaining or improving other properties, including a higher carrier mobility and lower power usage. Then, the detailed process of manufacturing would be presented, together with a discussion on the extent to which CNT's tube-like structure and impurities are challenged to deposit onto large wafers, preventing it from mass production. Finally, there would be a brief analysis of the future implications of CNTFETs.