In the current extensive studies of layered two-dimensional （2D） materials, compared to hexagonal structures such as graphene, hBN, and MoS2, low- symmetry 2D materials have shown great potential for applications in...In the current extensive studies of layered two-dimensional （2D） materials, compared to hexagonal structures such as graphene, hBN, and MoS2, low- symmetry 2D materials have shown great potential for applications in anisotropic devices. Rhenium diselenide （ReSe2） possesses the bulk space group P1 and belongs to the triclinic crystal system with a deformed cadmium-iodide-type structure. Here, we propose an electron diffraction-based method to distinguish the monolayer ReSe2 membrane from multilayer ReSe2 and its two different vertical orientations. Our method is also applicable to other low-symmetry crystal systems, including both triclinic and monoclinic lattices, as long as their third unit-cell basis vectors are not perpendicular to the basal plane. Our experimental results are well explained by kinematical electron diffraction theory and the corresponding simulations. Generalization of our method to other 2D materials, such as ~：raphene, is also discussed.展开更多
基金This work is financially supported by the National Basic Research Program of China （Nos. 2014CB932500 and 2015CB921004）, the National Natural Science Foundation of China （Nos. 51472215, 51222202, 61571197 and 61172011）, the 111 project （No. B16042） and MOST 104-2112-M-011-002-MY3. The authors would like to thank Prof. Christoph Koch fromHumbold University of Berlin for the fruitful dis- cussions on multislice simulations. J. Y. acknowledges the EPSRC （UK） funding （Nos. EP/G070326 and EP/ J022098） and supports from Pao Yu-Kong International Foundation for a Chair Professorship in ZJU. This work made use of the resources of the Center of Electron Microscopy of Zhejiang University
文摘In the current extensive studies of layered two-dimensional （2D） materials, compared to hexagonal structures such as graphene, hBN, and MoS2, low- symmetry 2D materials have shown great potential for applications in anisotropic devices. Rhenium diselenide （ReSe2） possesses the bulk space group P1 and belongs to the triclinic crystal system with a deformed cadmium-iodide-type structure. Here, we propose an electron diffraction-based method to distinguish the monolayer ReSe2 membrane from multilayer ReSe2 and its two different vertical orientations. Our method is also applicable to other low-symmetry crystal systems, including both triclinic and monoclinic lattices, as long as their third unit-cell basis vectors are not perpendicular to the basal plane. Our experimental results are well explained by kinematical electron diffraction theory and the corresponding simulations. Generalization of our method to other 2D materials, such as ~：raphene, is also discussed.
