Kinetic Nature of Grain Boundary Formation in As-Grown MoS2 Monolayers

Grain boundaries in as‐grown polycrystalline MoS2 monolayers are revealed by second‐harmonic‐generation microscopy. Through the anisotropic polarization pattern and phase interference at the grain boundary, grain edge termination and boundary types are identified. Statistical analysis on hundreds of grains shows that grain‐boundary formation is driven by kinetics and can be nicely described by the edge attachment growth model.