First-principles study of the structural and electronic properties of armchair silicene nanoribbons with vacancies

Using the first-principles calculations, we investigate the structural and electronic properties of the armchair silicene nanoribbons (ASiNRs) with a monovacancy or a divacancy. We find that either a monovacancy or a parallel oriented divacancy changes a direct semiconductor ASiNR to an indirect one, while a slanting oriented divacancy changes it to a metallic character. However, neither a monovacancy nor a divacancy can change the nonmagnetic character of the ASiNR even the metallic ASiNR with a slanting oriented divacancy. Furthermore, the optimized vacancy structure and the electronic properties are independent of the vacancy positions relative to the edge of the nanoribbon.