Effects of 48 defects and external electric field on the electronic properties of silicene nanoribbons

First-principles calculations based on density functional theory have been performed to investigate the topological defects effect and the influence of applied electric field on the electronic properties of perfect and 48 defects silicene nanoribbons (48D-SiNRs). The calculated results show that 48 defects will change 6ZsiNRs (Zigzag SiNRs with ribbon width of 6) from metal properties to semiconductor properties, and the bandgap of 6AsiNRs (Armchair SiNRs) from 0.3 eV to 0.07 eV. In addition, the 48D-6ZSiNRs is a direct bandgap semiconductor with 0.17 eV bandgap, and the 48D-6ASiNRs will turn to indirect bandgap from pristine direct bandgap. It can be found that the 48D-6ZSiNRs will close its bandgap and show metal properties with the 48 defect concentrations increasing. What is more, we investigate the impacts of an electric field on the electronic properties of the 48D-6ZSiNRs and 6ZSiNRs. The calculated results show that the bandgap of the 6ZSiNRs will change with its strength, and the 48D-6ZSiNRs change from semiconductor to metal properties when the external electric field is applied along the X direction. (paper)