Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 113: 2D materials beyond graphene: TMDCs, silicene and relatives V

O 113.6: Talk

Friday, March 16, 2018, 11:45–12:00, MA 043

Evolution of defects in two-dimensional MoTe₂: from point to extended defects — •Mahdi Ghorbani-Asl¹, Tibor Lehnert², Janis Köster², Hannu-Pekka Komsa³, Ute Kaiser², and Arkady Krasheninnikov^1,3 — ¹Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden, Germany — ²Electron Microscopy Group of Materials Science, University of Ulm, Ulm 89081, Germany — ³Department of Applied Physics, Aalto University, P.O. Box 11100, 00076 Aalto, Finland

Defects frequently govern the characteristics of solids, e.g., mechanical or optical properties. They also provide an efficient way to engineer materials properties, similar to doping in semiconductors. Using first-principles calculations combined with high-resolution transmission electron microscopy experiments, we study creation, agglomeration, and evolution of vacancies in monolayer MoTe₂ under electron irradiation. Various types of point and extended defects are studied and their atomic structures and formation energies are determined. The stability of flower-like defects and trefoil-like defects are compared with the line vacancies. Our results show that single Te vacancies have a tendency for agglomeration into vacancy lines. The stability of line defects is also found to be dependent on their orientation. We have also studied the effects of uniaxial and biaxial strain on the stability and dynamics of line defects. Our electronic structure calculations show that the defects can change the electronic properties of MoTe₂, suggesting new opportunities for defect engineering in these layered materials.