Theoretical Study of the Impact and Control of Topological Defects on the Electrical Properties of Single-Walled Carbon Nanotubes: Implications for Carbon-Based Transistor Regulation

Single-wall carbon nanotubes (SWCNTs) have unique electrical properties, making them potential silicon and copper replacements in semiconductors and nanointerconnects. Current research focuses on single vacancy defects, needing expansion to other topological defects. In this study, we account for the presence of topological defects and develop a model that demonstrates their impact on the electrical properties of carbon nanotubes (CNTs) by using a degradation coefficient for the conductivity. This study employs density functional theory combined with the nonequilibrium Green’s function method to systematically analyze the influence of various topological defects on the electronic structure and transport characteristics of SWCNTs, using I–V curves, transmission spectra, and 3D transmission spectra. The results indicate that defects of the same type substantially degrade the electronic transport properties of CNTs, with the degree of degradation varying based on the defects’ positions and quantities. This degradation can result in a reduction of over 20% in the electronic transport capacity compared with ideal CNTs. A linear positive correlation exists between the extent of degradation and the magnitude of the defects. Furthermore, the presence of a small number of 5–8–5 defects and Stone–Wales defects can induce bandgap opening from 0.109 to 0.549 eV for the bandgap of (6,6) CNTs. However, a high defect concentration reduces the bandgap, potentially to zero. Notably, regardless of whether the bandgap increases or decreases, the bandgap of (6,6) CNTs remains smaller than the bandgap of (11,0) semiconductor CNTs, leading to the transition of SWCNTs to metallic conductors. Finally, the differential conductivity diagram of CNTs with topological defects was analyzed, demonstrating that introducing specific 5–8–5 defects can effectively regulate the electrical properties of the CNTs. This paper analyzes the effects of defects on the CNTs electrical properties and finds a regulatory effect, providing a reference for carbon-based transistor manufacturing.