Tunnelling Characteristics of Stone-Wales Defects in Monolayers of Sn and Group- V Elements
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Date
2017
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Institute of Physics (IOP)
Abstract
Topological defects in ultrathin layers are often formed during synthesis and processing, thereby, strongly influencing the electronic properties of the layered systems. For the monolayers of Sn and group-V elements, we report the results based on density functional theory determining the role of Stone-Wales (SW) defects in modifying their electronic properties. The calculated results find the electronic properties of Sn monolayer to be strongly dependent on the concentration of SW-defects e.g., defective stanene has nearly zero band gap (≈ 0.03 eV) for the defect concentration of 2.2 x 10<sup>13</sup> cm<sup>-2</sup> which opens up to 0.2 eV for the defect concentration of 3.7 x 10<sup>13</sup> cm<sup>-2</sup>. In contrast, SW-defects appear to induce conduction states in the semiconducting monolayers of group-V elements. These conduction states act as channels for electron tunnelling, and the calculated tunnelling characteristics show the highest differential conductance for the negative bias with the asymmetric current-voltage characteristics. On the other hand, the highest differential conductance was found for the positive bias in stanene. Simulated STM topographical images of stanene and group-V monolayers show distinctly different features in terms of their cross-sectional views and distance-height profiles. These distinctive features can serve as fingerprints to identify the topological defects in experiments for the monolayers of group-IV and group-V elements.
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Tunnelling Characterstics of Stone-Wales Defects in Monolayers of Sn and Group-V Elements” Pooja Jamdagni, Ashok Kumar, Anil Thakur, Ravindra Pandey, P. K. Ahluwalia Journal of Physics:Condensed Matter (Accepted) DOI: 10.1088/1361-648X/aa7dd1