Peking University researcher realizes the preparation of decimeter-level single crystal monolayer hexagonal boron nitride

On May 22, London time, a paper published by Nature magazine stated that scientists and collaborators from Peking University used the center to invert the symmetry to break the substrate and successfully achieved the first decimeter-level two-dimensional hexagonal boron nitride single Epitaxy of crystals. This is another major progress in the field of single crystal growth of two-dimensional materials following the successful preparation of meter-grade graphene single crystals.

The rise of two-dimensional materials has opened up huge possibilities for potential applications in the fields of electronics, optoelectronics, and photovoltaics because of their smaller size, higher speed, and newer functions. The preparation of large-area, high-quality basic two-dimensional single crystal materials (two-dimensional conductor graphene, two-dimensional semiconductor transition metal chalcogenide compounds, black phosphorus, etc. and two-dimensional insulator hexagonal boron nitride) is a large-scale application of two-dimensional devices Core. Among them, hexagonal boron nitride (hBN) has excellent stability, the surface is flat without dangling bonds, and it is the best known two-dimensional insulator. However, the size of single-crystal two-dimensional hexagonal boron nitride has always been a huge challenge in the field of nanomaterials, mainly because the triple symmetrical hexagonal boron nitride lattice epitaxially grows on the surface of conventional metal substrates and reverse crystal domains appear, which leads A large number of defective grain boundaries are generated. After years of research, the research group and collaborators of Peking University Liu Kaihui found that industrial copper foil can be transformed into a â€œneighboring crystal planeâ€ with a certain inclination angle to the (110) crystal plane through a special annealing process, and 10 Ã— 10 cm2 single crystal hexagonal boron nitride single-layer epitaxial growth. The results of various characterization methods and theoretical calculations indicate that the key to epitaxial growth is the coupling of Cu <211> steps and hexagonal boron nitride lattice nitrogen cut-off sawtooth edges. This coupling effect can break the advantage of reverse crystal domain orientation, so that all crystal domain orientations are seamlessly spliced â€‹â€‹into a single crystal with this one.

Previously, it has been difficult to achieve large-scale single crystal preparation for the vast majority of two-dimensional materials composed of two elements. The successful research of this paper will provide reference for the preparation of other two-dimensional materials.

Wang Li, Xu Xiaozhi, Zhang Leining and Qiao Ruixi are the co-first authors of the paper, and Liu Kaihui, Ding Feng, Wang Zhujun and Bai Xuedong are the corresponding authors. Other collaborators of the paper include: Wang Enge, Yu Dapeng, Jiang Ying, Zhang Yi, Wu Shiwei, Gao Peng, Wang Wenlong, Li Qunyang, Wu Hui, Marc Willinger, etc.

Fig.1 Preparation and characterization of large area single crystal Cu (110) substrate.