Multiscale insights into screw dislocation-driven growth mechanisms

Spiral growth in two-dimensional (2D) materials has conventionally been explained by single screw dislocation mechanisms, yet a complete multiscale understanding remains elusive due to the intricate nature of screw dislocation structures. Here, we present a stabilization approach through metallic transition metal dichalcogenides (m-TMDs) overlayers on spiral semiconducting TMDs (s-TMDs), which enables unprecedentedly robust atomic-resolution imaging of screw dislocations in cross-sectional van der Waals heterostructures. Our multiscale investigations identify nanoscale substrate undulations as critical nucleation sites for screw dislocations and uncover a multi-screw dislocation-driven (MSDD) growth paradigm, characterized by periodic stress stripes with linear densities approaching ∼10⁶ cm^-1. Furthermore, we establish that dislocation interactions govern stacking sequence reconstruction, while the kinetic competition among multiple screw dislocations determines the ultimate spiral architectures. These insights fundamentally transform our understanding of defect-mediated growth in 2D materials.