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. (C) 2011 Elsevier B.V. All rights reserved.