Extended Data Fig. 8: Heterobilayer moiré pattern for twist angles close to 21.8°.

a–c, Three high-symmetry stacking patterns exist for the heterobilayer with a commensurate 21.8° twist angle, in which the two layers have the same lattice constant a. The dashed diamonds indicate the smallest supercells, the periodicity of which is \(\sqrt{7}a\). The large (small) solid green dots denote the metal, M (chalcogen, X) sites in the electron layer, whereas the large (small) empty orange dots denote the metal, M (chalcogen, X) sites in the hole layer. a, The stacking in which two M sites in different layers horizontally overlap. b, The stacking in which two hexagon centres (h sites) in different layers horizontally overlap. c, The stacking in which two X sites in different layers horizontally overlap. Because M, X and h are the C₃ rotation centres of the monolayers, the stacking configurations in a, b and c are all C₃ symmetric. d, Illustration of the moiré pattern when the twist angle slightly deviates from 21.8° (θ = 20° here). Red circles marked by A, B and C are the local regions that are nearly indistinguishable from the commensurate 21.8° pattern in a, b and c, respectively. The black diamonds are the \(\sqrt{7}a\times \sqrt{7}a\) supercells of the local regions.