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., Cu 2 O. It is revealed thermodynamically that the unidirectional nucleation of h -BN can be rationalized on the symmetry-matched Cu 2 O(111) surface rather than the antiparallel nucleation on the Cu(111) surface. Kinetically, the dehydrogenation of feedstock of h -BN on the Cu 2 O(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 Cu 2 O, which leads to a surface-diffusion-based growth behavior on the Cu 2 O(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.