Investigation on edge defect characteristics and electronic transport characteristics of graphene nano cutting

Abstract

The effects of cutting crystal direction and speed on edge morphology, defects and electron transport characteristics were studied by molecular dynamics from the distribution state of defect atoms, the number of defect atoms, cutting force and radial distribution function. The edge defects of zigzag graphene nanoribbons were extracted, and the difficulty of forming different kinds of defects and the influence of different defects on band gap were studied by density functional theory. The results indicate that cutting graphene along the [010] (zigzag) direction has a smaller variance and smoother cutting. The obtained graphene nanoribbons have fewer defects and good edge quality. And the higher the cutting speed, the fewer defects of the graphene nanoribbons formed, resulting in smaller damage. The typical defects at the edges include 5–8–5 defect (double-vacancy defect), 5–9 SV defect (single-vacancy defect), stone wales (SW) defect, chain defect, crack defect and hole defect. The relationship between the magnitude of forming energy values produced by different defect types is as follows: crack defect > chain defect > SW defect > 5–9 SV defect > 5–8–5 defect > hole defect. Hole defect is the most difficult to form. The band gap width of the cut edge containing defects is smaller than that of the perfect graphene nanoribbon, resulting in the increase of the conductivity of the graphene nanoribbon in the direction of metal characteristics. The presence of defects can open the band gap with of intrinsic graphene.