1D Edge state at a stacking fault boundary of WSe₂ monolayers

In 3D crystals, stacking fault represents a phase disruption of an otherwise periodic stacking of lattice planes. In 2D crystals, stacking fault presents the disruption of periodic stacking of atomic chains. The topic of stacking fault in 2D crystals has been discussed previously in both graphene and transition metal dichalcogenide monolayers [1-3]. However, most of the discussions have primarily focused on the structural aspect, albeit some have also touched upon the electronic structures. Here, we use scanning tunneling microscopy/spectroscopy (STM/STS) to investigate the atomic and electronic structure of a 1D stacking fault on a 2D atomic crystal (in this case, WSe2 monolayers). We identify the localized states and itinerant states along this 1D boundary. We further reveal the manifestation of this 1D edge channel under the influence of lateral electrostatic potential.

[1] Lahiri, J. et. al. Nature Nanotech 5, 326–329 (2010)

[2] Lu, J. et. al. ACS Nano 7, 8350–8357 (2013)

[3] Lin, Z. et. al. 2D Mater. 3 022002 (2016)