Defects in monolayer WS2 grown via sulfurization of WSe2

The conversion of chalcogen atoms into other types of chalcogen atoms in transition metal dichalcogenides exhibits significant advantages in tuning the bandgaps and constructing lateral heterojunctions. However, despite atomic defects at the atomic scale were inevitably formed during conversion process, the construction of dislocations remains difficult. Here, we conducted in-situ sulfurization to achieve structural transformation from monolayer WSe2 to WS2 successfully. We probe these transformations at atomic scale using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and study structural defects of sulfurizedWS2 by strain and displacement fields. We discovered that high-quality WSe2 flakes were completely sulfurized while dislocations were successfully constructed, manifesting atomic surface roughness and structural disorders. Our work provides insights into designing and optimizing customized Transition metal dichalcogenides (TMDs) materials in controlled synthesis and defect engineering.