Abstract
The interesting and tunable properties of layered metal dichalcogenides heavily depend on their
15 phase and layer stacking. Here, we show and explain how the layer stacking and physical
16 properties of WSe2 are influenced by screw dislocations. A one-to-one correlation of atomic force
17 microscopy and high- and low-frequency Raman spectroscopy of many dislocated WSe2
18 nanoplates reveals variations in the number and shapes of dislocation spirals and different layer
19 stackings that are determined by the number, rotation, and location of the dislocations. Plates with
20 triangular dislocation spirals form non-centrosymmetric stacking that gives rise to strong second-
21 harmonic generation and enhanced photoluminescence, plates with hexagonal dislocation spirals
22 form the bulk 2H layer stacking commonly observed, and plates containing mixed dislocation
23 shapes have intermediate non-centrosymmetric stackings with mixed properties. Multiple
24 dislocation cores and other complexities can lead to more complex stackings and properties. These
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25 previously unobserved properties and layer stackings in WSe2 will be interesting for spintronics
26 and valleytronics.
