posted on 2021-09-07, 13:04authored byYuzhou Zhao, Xiao Kong, Melinda J. Shearer, Feng Ding, Song Jin
Chemical etching can create novel
structures inaccessible by growth
and provide complementary understanding on the growth mechanisms of
complex nanostructures. Screw dislocation-driven growth influences
the layer stackings of transition metal dichalcogenides (MX2) resulting in complex spiral morphologies. Herein, we experimentally
and theoretically study the etching of screw dislocated WS2 and WSe2 nanostructures using H2O2 etchant. The kinetic Wulff constructions and Monte Carlo simulations
establish the etching principles of single MX2 layers.
Atomic force microscopy characterization reveals diverse etching morphology
evolution behaviors around the dislocation cores and along the exterior
edges, including triangular, hexagonal, or truncated hexagonal holes
and smooth or rough edges. These behaviors are influenced by the edge
orientations, layer stackings, and the strain of screw dislocations. Ab initio calculation and kinetic Monte Carlo simulations
support the experimental observations and provide further mechanistic
insights. This knowledge can help one to understand more complex structures
created by screw dislocations through etching.