Fig. 5: Shows defect generation and moiré patterns in the bilayer MoS₂ before and after the surface acoustic wave (SAW) passes through the constituent monolayers.

Here we zoom in far from the nanopore region to show SAW-induced changes in the structure and stress distribution. The green atoms are Mo and yellow are S. The left column shows the initial structures, the middle column shows the changes in moiré pattern and defects, and the right column shows the stress distribution. The phases in the middle column are 2H (blue), α defect (red), and other defects (yellow). a shows the two layers in perfect registry as the relative twist between the two monolayers θ = 0°. b shows the break in perfect registry when the SAW passes through the region and defects (red and yellow) form in regions of moiré patterns. c shows that stresses in defect regions are either very high or very low. d, e show the same phenomenon at θ = 0.5°, where the moiré pattern have transformed (panel e), the regions between defects (marked as 1) have similar patterns and there is a horizontal region between two domains where there is a new moiré pattern (marked as 2). The corresponding stress distribution is shown in panel f. At θ = 5°, the SAW propagation breaks the hexagonal moiré unit cells as shown in panels g and h. i shows the corresponding stress distribution.