Mechanism of Controllable Growth of Large-Area Single-Crystal Hexagonal Boron Nitride on Preoxidized Copper Substrate

Two-dimensional (2D) hexagonal boron nitride (h-BN) exhibits promising properties for electronic and photoelectric devices, while the growth of high-quality h-BN remains challenging. Here we theoretically explored the mechanism of epitaxial growth of high-quality h-BN by using the preoxidized and hydrogen-annealed copper substrate, i.e., Cu₂O. It is revealed thermodynamically that the unidirectional nucleation of h-BN can be rationalized on the symmetry-matched Cu₂O(111) surface rather than the antiparallel nucleation on the Cu(111) surface. Kinetically, the dehydrogenation of feedstock of h-BN on the Cu₂O(111) surface is also much easier than that on the Cu(111) surface. Both the B and N atoms are energetically more preferred to stay on the surface rather than inside the body of Cu₂O, which leads to a surface-diffusion-based growth behavior on the Cu₂O(111) surface instead of the precipitation-diffusion mixed case on the Cu(111) surface. Our work may guide future experimental design for the controllable growth of wafer-scale single-crystal h-BN.