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Matthieu Jamet1 Celine Vergnaud1 Minh-Tuan Dau1 Alain Marty1 Cyrille Beigne1 Carlos Álvarez1 Hanako Okuno1 Maxime Gay1 Olivier Renault1 Gilles Renaud1 Jean-François Jacquot1

1, CEA Grenoble, Grenoble, , France

Top-down exfoliation from bulk transition metal dichalcogenides like MoS2 usually leads to micron-sized flakes. We have recently developed an alternative growth method of two-dimensional transition metal diselenides (TMDS) from multilayers down to a single layer based on the Van der Waals (VdW) epitaxy. In the VdW epitaxy, the TMDS is grown either on a passivated surface with a very low density of dangling bonds (it is then called quasi-VdW epitaxy) or on a layered VdW substrate. The basic concept of this growth method relies on the very weak interaction between the epilayer and the substrate in order to largely release the constraint of lattice matching. Therefore it leads to the formation of fully relaxed TMDS layers. Moreover, this technique allows for the growth of uniform layers over centimeter scale surfaces making it compatible with the development of a large scale 2D electronics based on these materials. Using VdW epitaxy, we have recently grown MoSe2 and WSe2 multi and monolayers on various substrates: SiO2, epitaxial graphene [M.-T. Dau et al., ACS Nano 12, 2319 (2018)], mica and selenium passivated platinum crystal. Owing to our ability to deposit two transition metals simultaneously, we have explored electrical and magnetic doping of TMDS. In this presentation, we will show our recent results on three different topics relying on the VdW epitaxy: (i) the epitaxy of multi and monolayers of p-type doped (with Nb) WSe2 and magnetically doped (with Mn) MoSe2 on mica, graphene and platinum crystal, (ii) the full characterization of the layers using Raman and photoemission spectroscopies, x-ray diffraction, transmission electron microscopy and SQUID magnetometry and (iii) their transfer onto a SiO2/Si substrate to study electrical and magnetotransport properties. In particular, we find a ferromagnetic order in Mn-doped MoSe2 layers at low temperature adding a new member to the recently discovered 2D ferromagnets family [C. Gong et al., Nature 546, 265 (2017), B. Huang et al., Nature 546, 270 (2017), M. Bonilla et al., Nature Nanotech. 13, 289 (2018)].

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