Bevel-edge epitaxy of ferroelectric rhombohedral boron nitride single crystal

L Wang and JJ Qi and WY Wei and MQ Wu and ZB Zhang and XM Li and HC Sun and QL Guo and M Cao and QH Wang and C Zhao and YX Sheng and ZT Liu and C Liu and MH Wu and Z Xu and WL Wang and H Hong and P Gao and MH Wu and ZJ Wang and XZ Xu and EE Wang and F Ding and XR Zheng and KH Liu and XD Bai, NATURE, 629, 74-79 (2024).

DOI: 10.1038/s41586-024-07286-3

Within the family of two-dimensional dielectrics, rhombohedral boron nitride (rBN) is considerably promising owing to having not only the superior properties of hexagonal boron nitride1-4-including low permittivity and dissipation, strong electrical insulation, good chemical stability, high thermal conductivity and atomic flatness without dangling bonds-but also useful optical nonlinearity and interfacial ferroelectricity originating from the broken in-plane and out-of-plane centrosymmetry5-23. However, the preparation of large-sized single-crystal rBN layers remains a challenge24-26, owing to the requisite unprecedented growth controls to coordinate the lattice orientation of each layer and the sliding vector of every interface. Here we report a facile methodology using bevel-edge epitaxy to prepare centimetre-sized single-crystal rBN layers with exact interlayer ABC stacking on a vicinal nickel surface. We realized successful accurate fabrication over a single-crystal nickel substrate with bunched step edges of the terrace facet (100) at the bevel facet (110), which simultaneously guided the consistent boron-nitrogen bond orientation in each BN layer and the rhombohedral stacking of BN layers via nucleation near each bevel facet. The pure rhombohedral phase of the as-grown BN layers was verified, and consequently showed robust, homogeneous and switchable ferroelectricity with a high Curie temperature. Our work provides an effective route for accurate stacking-controlled growth of single-crystal two-dimensional layers and presents a foundation for applicable multifunctional devices based on stacked two-dimensional materials. Centimetre-sized single-crystal rhombohedral boron nitride layers are achieved through bevel-edge epitaxy, and the resulting material exhibits robust, homogeneous and switchable ferroelectricity with a high Curie temperature.

Return to Publications page