Carbon Nanotube Necking Topological Defect Engineering Offers Electrical Property Modulation and Control with Implications in Nonlinear Nanoelectronic Devices

This study investigates the electrical property modulation of single-walled carbon nanotubes through the engineering of necking topological defects induced by plastic deformation. Combining molecular dynamics simulations and first-principles calculations (density functional tight-binding coupled with nonequilibrium Green’s function formalism), we demonstrate that controlled tensile loading at 3500 K generates stable necking configurations with Stone–Wales-like defects and 5–8–5 vacancy defects when strain rates are maintained within 8–11%. System analysis reveals that the 5–8–5 defect primarily suppresses electron transport through two mechanisms: creating a transmission trough near 0.14 eV and introducing multiple low-transmission troughs within the bias voltage window. These effects induce nonlinear current–voltage characteristics with conductance plateaus in the ±1.2 V range, mimicking the behavior of semiconductor heterojunction rectification. In contrast, SW-like defects cause partial attenuation of the transmission coefficient without forming a significant bandgap. Necking diameter reduction exhibits a strong positive correlation with conductivity degradation, while axial necking length (4–12-unit cells) shows a negligible impact. The 5–8–5 defect-mediated structures demonstrate superior potential for creating functional molecular junctions compared to SW-like configurations. By establishing the correlation between plastic deformation parameters (temperature, strain rate), necking geometry (diameter, defect type), and electron transport characteristics of carbon nanotubes, this paper provides an approach for designing carbon-based nanodevices based on mechanical strain regulation. It opens an avenue for researching carbon-based nonlinear nanoelectronic devices.