2D-BN growth on nickel under ultra-high vacuum conditions from borazine

National audience; Graphene is a 2D material, famous for its exceptional electronic properties. However, to exploit these properties in real devices, the electronic coupling with the substrate and with any surrounding material must be strongly reduced. Hexagonal boron nitride (hBN), another 2D material, is very promising for this purpose [1]. It could be used both to insulate graphene from the substrate and as a gate dielectric material. Although devices obtained by mechanical exfoliation and transfer did confirm the strong potentialities of graphene/hBN heterostructures [2], a scalable and reliable growth technique remains to be demonstrated: the development of new in situ approaches to the fabrication of graphene/BN 2D heterostructures is of high importance. If scalable graphene growth is now well documented [3], this is not yet the case for 2D-BN. The ultimate goal is to be able to grow 2D-BN film with accurate thickness control from one to few layers on graphene as well as on technologicallycompatible substrates. Towards this goal, we have started studying the growth of 2D-BN on Ni substrates using the gaseous borazine precursor (B3N3H6), either used alone [4] or combined with to a complementary source of N provided by a plasma cell. Experiments were done in a molecular beam epitaxy chamber. A continuous h-BN film is obtained when using the only precursor borazine, with a self-limited thickness of one monolayer [5] .When using combined borazine-nitrogen sources, high quality material is locallyobtained but with a rather heterogeneous thickness and a dependent quality to the crystal orientation of the substrate.