Defect Migrations in Hexagonal Boron Nitride Moiré Superlattices

Twisting bilayer hexagonal boron nitride (hBN) by a small twist angle creates a large-area moiré superlattice with triangular domains of AB and BA stackings separated by a thin shear domain wall (DW). Recent experimental observations using low-energy electron microscopy and photoelectron emission microscopy reveal a strong trend of point defects aligning to DW regions as opposed to the AB/BA stacking domains. We employ a multiscale computational framework combining classical force field simulations and density functional theory calculations to investigate the correlation between structural reconstruction in hBN and defect energetics. By analyzing the formation energies of various point defects in hBN, we study how local strain fields in reconstructed domain walls modify the energy landscape for defect formation compared to pristine AA and AB/BA stacking regions. Our calculations provide insights into the mechanism of defect migration in twisted van der Waals heterostructures.