Figure 2.

a) The bandgap structure of MoTe₂ from four layers to monolayer. Reproduced with permission.35 Copyright 2015, American Chemical Society. b) The bandgap of monolayer MoTe₂ is 1.16 eV. Crystalline structure of Td WTe₂. Reproduced with permission.8 Copyright 2014, Springer. c) Perspective view. d) Front view and side views. e) Top view. The grains and grain boundaries of monolayer MoTe₂ were observed by polarized optical microscopy. Reproduced with permission.99 Copyright 2016, the authors, published under CC‐BY‐4.0 license. f) The grain can be clearly observed in 5°–10° of the polarizer rotation near 85°. g) Under perfectly crossed polarizer–analyzer (P–A) setup, nothing can be seen. Reproduced with permission.98 Copyright 2014, IOP Publishing.