Dresden 2020 – scientific programme

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DS: Fachverband Dünne Schichten

DS 28: Poster: Thin Film Properties: Structure, Morphology and Composition

DS 28.9: Poster

Wednesday, March 18, 2020, 15:00–18:00, P1A

Electron beam induced defect formation and evolution in single-layer WSe₂ — •Robert Leiter, Yueliang Li, and Ute Kaiser — Electron Microscopy Group of Materials Science, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany

Lattice defects in two-dimensional TMD monolayers, such as tungsten diselenide (WSe₂) can alter the electronic properties of the material [1]. Artificially creating such defects by means of an electron beam may be used to tailor the structure and properties of these monolayers for use in future devices [2].

Here, we use the C_c/C_s - corrected SALVE (Sub Ångström Low Voltage Electron microscopy) instrument to observe the dynamics of the formation and evolution of defects in WSe₂ atom by atom [3]. Single point defects are highly mobile and accumulate fast to more extended defects. With continued electron beam irradiation, inversion domains form, which contain several types of mirror twin boundaries (MTBs), previously reported to possess interesting electrical and magnetic properties. We also observe MTBs that were previously unreported for tungsten diselenide as well as a completely new type of boundary, not reported in any TMD so far. We show that with further increased electron dose, highly defective W-rich regions within the WSe₂ matrix form, paving interesting ways towards device engineering.

[1] Y.-C. Lin et al., Nat. Commun. 6, 6736 (2015)

[2] H.-P. Komsa and A. V. Krasheninnikov, Adv. Electron. Mater. 3, 1600468 (2017)

[3] M. Linck et al., Phys. Rev. Lett. 117, 076101 (2016)