Formation of Large-Area Twisted Bilayer Graphene on Ni(111) Film via Ambient Pressure Chemical Vapor Deposition

Abstract

Due to the destruction of the intrinsic symmetry between the layers, twisted bilayer graphene has the advantages of available interlayer coupling, tunable electronic bandgap, and diverse phonon dispersion features, which offers a unique platform for the advanced electronic devices. The segregation growth of large-area twisted bilayer graphene on Ni(111) film by ambient pressure chemical vapor deposition (APCVD) methods is presented in this paper. The growth kinetics include two main aspects of the catalytic reaction of methane on the Ni surface and the carbon segregation from the Ni bulk. The large-area twisted bilayer graphene (TBG) can be fabricated by controlling carbon segregation for the continuous second layer graphene that is rotated relative to the first layer graphene. Low energy electron diffraction (LEED) studies reveal a dominant twist angle of about 22.7°. The analysis shows that the dominant twist angle is closely related to the stable energy structure of TBG with the smallest moiré periodicity. Besides, the other twist angles of TBG are also formed in vicinity of the dominant angle, confirmed by microscopic observations with selected area electron diffraction (SAED). The work in this paper provides a convenient route for the synthesis of TBG on Ni(111) substrate, which can promote the application of twisted graphene in future photoelectric and spintronic devices.