Mirror twin boundaries in WSe2 induced by vanadium doping

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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2023-06

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en

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Materials Today Nano, Volume 22

Abstract

Mirror twin boundaries (MTBs) observed in MoSe2 are formed due to incorporation of excess Mo into the lattice. In contrast, MTBs in WSe2 have a high formation energy and consequently are not present in this system. Here we show that V-doping of WSe2, achieved by co-deposition of V and W during molecular beam epitaxy (MBE) growth of WSe2, can also induce MTB formation in WSe2, as revealed by scanning tunneling microscopy. Our experimental results are supported by density functional theory calculations that show that V-doped WSe2 is susceptible to the incorporation of more V-atoms at interstitial sites. This increases the transition metal atom concentration in the lattice, and these excess atoms rearrange into MTBs, which is associated with energy lowering of the excess metal atoms. While formation of MTBs gives rise to the pinning of the Fermi-level and thus prevents V-induced electronic doping, MTBs do not appear to affect the magnetic properties, and a diluted ferromagnetic material is observed for low V-doping levels, as reported previously for V-doped WSe2.

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Funding Information: Financial support from the National Science Foundation under award DMR 2118414 is acknowledged. We further acknowledge funding from the German Research Foundation (DFG), project KR 4866/6–1, and through the collaborative research centre “Chemistry of Synthetic 2D Materials” SFB-1415- 417590517. The authors wish to acknowledge CSC – IT Centre for Science, Finland, for computational resources. We also thank the Gauss Centre for Supercomputing e.V. ( www.gauss-centre.eu ) for providing computing time on the GCS Supercomputer HAWK at Höchstleistungsrechenzentrum Stuttgart ( www.hlrs.de ) and also TU Dresden (Taurus cluster) for generous grants of CPU time.

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Pathirage , V , Lasek , K , Krasheninnikov , A V , Komsa , H P & Batzill , M 2023 , ' Mirror twin boundaries in WSe 2 induced by vanadium doping ' , Materials Today Nano , vol. 22 , 100314 . https://doi.org/10.1016/j.mtnano.2023.100314