Several challenges, such as the short-channel effect and poor electron transport, still exist in the application of silicon-based materials in the application of integrated circuits despite wide utilization. Through ongoing research and development, we have discovered that carbon-based materials hold significant practical potential. Doping is one of the modification methods for carbon-based materials and has increasingly become a focus of research [1,2]. Since Iijima’s discovery, carbon nanotubes (CNTs) have gathered significant interest globally due to their excellent mechanical and electrical properties. They have been synthesized and applied in various fields [3,4]. CNTs are now among the most studied materials due to their advantages in length-to-diameter ratio, electrical conductivity, and structural stability [5,6]. Carbon atoms substitution can be easily achieved in numerous synthetic methods, and nitrogen atoms are selected as an ideal dopant due to its similar electronic structure and electronegativity. Nitrogen doping enhances the conductivity, field electron emission properties, and chemical activity of CNTs toward gas molecules [7]. Jaclyn D [8] investigated the impact of heteroatomic doping (e.g., boron and nitrogen) on the physicochemical properties of sp² carbon materials. It was evident that N doping and the resulting degradation of the carbon lattice structure would lead to changes in electron transport. San et al. [9] examined the impact of nitrogen doping in four types of single-walled carbon nanotubes and found that both amino functional groups and substitutional doping had significant effects. Yu et al. [10] and Shao et al. [11] found that doping single-walled carbon nanotubes leads to an upward shift in the Fermi energy level and a decrease in the work function, resulting in increased electrical conductivity. Allali et al. [12] demonstrated that the electronic properties of nitrogen-doped nanotubes are related not only to the concentration of nitrogen atoms but also to their distribution in nanotubes. Ayala et al. [13] described the properties of doped carbon nanotubes and hybrid nanotubes formed by stable carbon and nitrogen-containing chemical groups, respectively. Wang et al. [14] conducted pioneering research on the effect of doping on electron transport in ultrafine carbon nanotube devices. They found that the electron transport properties are influenced by the spatial distribution of doping impurities. The optimal transport properties were observed when impurities were linearly distributed along the carbon nanotube axis. Therefore, we focus on studying longitudinal linear doping patterns. We investigated the effects of doping mode and nanotube length on electron transport based on previous research on doped single-walled carbon nanotubes. Zigzag (8,0) carbon nanotubes primarily exhibit semiconductor properties. Since the electronic properties of CNTs are strongly dependent on their atomic structure, mechanical deformations or chemical doping can induce significant changes in conductance [15].

In this study, energy band, density of states, voltammetry characteristic curves, and differential charge density are analyzed to investigate the structure and properties of carbon nanotubes with various nitrogen doping configurations. Linearly doped zigzag (8,0) CNTs are divided into two groups for straightforward comparison.