Epitaxial relationship between MoSe₂ and C-sapphire. (A, B) RHEED pattern of MoSe₂/sapphire along Al₂O₃ and directions, respectively. The white and red arrows denote diffraction patterns from sapphire and MoSe₂, respectively. (C, D) Cross-sectional HAADF-STEM images of the as-grown MoSe₂/Al₂O₃ interface along Al₂O₃ and directions, respectively. (E, F) Schematic of the atomic arrangement along Al₂O₃ and directions, respectively. (G) The epitaxial relationship of MoSe₂ on sapphire (0001) substrate. Red and blue arrows indicate the lattice vectors of sapphire and MoSe_2.