title: Point defects in lines in single crystalline phosphorene: directional migration and tunable band gaps.
abstract: Extended line defects in two-dimensional (2D) materials can play an important role in modulating their electronic properties. During the experimental synthesis of 2D materials, line defects are commonly generated at grain boundaries between domains of different orientations. In this work, twelve types of line-defect structures in single crystalline phosphorene are examined by using first-principles calculations. These line defects are typically formed via migration and aggregation of intrinsic point defects, including the Stone-Wales (SW), single or double vacancy (SV or DV) defects. Our calculated results demonstrate that the migration of point defects in phosphorene is anisotropic, for instance, the lowest migration energy barriers are 1.39 (or 0.40) and 2.58 (or 0.49) eV for SW (or SV) defects in zigzag and armchair directions, respectively. The aggregation of point defects into lines is energetically favorable compared with the separated point defects in phosphorene. In particular, the axis of line defects in phosphorene is direction-selective, depending on the composed point defects. The presence of line defects effectively modulates the electronic properties of phosphorene, rendering the defect-containing phosphorene either metallic or semiconducting with a tunable band gap. Of particular interest is the fact that the SV-based line defect can behave as a metallic wire, suggesting a possibility to fabricate a circuit with subnanometer widths in the semiconducting phosphorene for nanoscale electronic application.
authors.affiliation: CAS Key Laboratory of Materials for Energy Conversion, School of Chemistry and Materials Sciences, and CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui 230026, China and Hefei National Laboratory of Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation of Quantum Information & Quantum Technology, University of Science and Technology of China, Hefei, Anhui 230026, China. xjwu@ustc.edu.cn and Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
authors.forename: Xiuling
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
authors.forename: Liang
authors.identifier: http://orcid.org/0000-0003-4747-613X
authors.initials: L
authors.lastname: Ma
authors.affiliation: CAS Key Laboratory of Materials for Energy Conversion, School of Chemistry and Materials Sciences, and CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui 230026, China and Hefei National Laboratory of Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation of Quantum Information & Quantum Technology, University of Science and Technology of China, Hefei, Anhui 230026, China. xjwu@ustc.edu.cn.
authors.forename: Dayong
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
authors.forename: Xiao Cheng
authors.initials: XC
authors.lastname: Zeng
authors.affiliation: CAS Key Laboratory of Materials for Energy Conversion, School of Chemistry and Materials Sciences, and CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui 230026, China and Hefei National Laboratory of Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation of Quantum Information & Quantum Technology, University of Science and Technology of China, Hefei, Anhui 230026, China. xjwu@ustc.edu.cn.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Wu
authors.affiliation: Hefei National Laboratory of Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation of Quantum Information & Quantum Technology, University of Science and Technology of China, Hefei, Anhui 230026, China. xjwu@ustc.edu.cn.
authors.forename: Jinlong
authors.initials: J
authors.lastname: Yang