2, Department of Applied Physics, Aalto University, Helsinki, , Finland
Line defects, such as vacancy agglomerations and grain boundaries, strongly affect the properties of 2D, see Ref.  for an overview. The effects can be not only detrimental, but also beneficial in transition metal dichalcogenides (TMDs), so that controlling the density and type of the boundaries in these systems should be important for engineering their properties. In my presentation, I will touch upon the energetics and formation mechanisms of mirror twin boundaries in various TMDs during their growth  or under electron irradiation [2-4] and post-synthesis deposition of Mo atoms  with the main focus on the theoretical results obtained using DFT calculations in collaboration with several experimental groups. I will also discuss how controllable introduction of mirror twin boundaries and inversion domains can be used to add new functionalities to 2D TMDs.
1. H.-P. Komsa and A. V. Krasheninnikov, Advanced Electronic Materials 3 (2017) 1600468.
2. O. Lehtinen, H.-P. Komsa, A. Pulkin, M.B. Whitwick, M.-W. Chen, T. Lehnert, M. Mohn, O.V. Yazyev, A. Kis, U. Kaiser, and A. V. Krasheninnikov, ACS Nano 9 (2015) 3274.
3. Y.-C. Lin, T. Björkman, H.-P. Komsa, P.-Y. Teng, C.-H. Yeh, F.-S. Huang, K.-H. Lin, J. Jadczak, Y.-S. Huang, P.-W. Chiu, A. V. Krasheninnikov, and K. Suenaga, Nature Communications 6 (2015) 6736.
4. T.Lehnert, M. Ghorbani-Asl, J. Köster, Z. Lee, A.V. Krasheninnikov and U. Kaiser, to be published.
5. P. M. Coelho, H.-P. Komsa, H. C. Diaz, Y. Ma, A. V. Krasheninnikov, and M. Batzill, ACS Nano 12 (2018) 3975.