Two-dimensional layered MoSi2N4 material family discovered by metals

[ Instrument Network Instrument R&D ] On August 7, the advanced carbon materials research department of Shenyang National Research Center for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, made progress in new two-dimensional materials, titled Chemical vapor deposition of layered two-dimensional MoSi2N4 materials, Published online on Science.

Two-dimensional van der Waals layered materials represented by graphene have unique electrical, optical, mechanical, thermal and other properties, and have broad application prospects in the fields of electronics, optoelectronics, energy, environment, aerospace and other fields. At present, widely studied two-dimensional layered materials, such as graphene, boron nitride, transition metal chalcogenides, black phosphorene, etc., all have known three-dimensional matrix materials. The exploration of two-dimensional layered materials without known three-dimensional matrix materials can expand the physical properties and applications of two-dimensional materials, which has important scientific significance and practical value.

In 2015, the team of Ren Wencai and Cheng Huiming of the Shenyang National Research Center for Materials Science invented a bimetal substrate chemical vapor deposition (CVD) method to prepare a variety of non-layered two-dimensional transition metal carbide crystals with different structures, such as orthorhombic Mo2C , Hexagonal WC and cubic TaC, and found that ultra-thin Mo2C is a two-dimensional superconductor (Nature Materials, 2015). However, constrained by surface energy, non-layered materials rich in surface dangling bonds tend to grow in islands, making it difficult to obtain a single-layer material with uniform thickness.

The team recently discovered that in the process of CVD growth of non-layered two-dimensional molybdenum nitride, the introduction of silicon can passivate the dangling bonds on the surface, thereby preparing a new two-dimensional van der Waals layer without known parent materials Shape material MoSi2N4, and obtain a centimeter-level single-layer film. A single layer of MoSi2N4 contains 7 atomic layers of N-Si-N-Mo-N-Si-N, which can be regarded as a single layer of MoN (N-Mo-N) sandwiched between two Si-N layers. Using a similar method, a single layer of WSi2N4 was also prepared.

On this basis, the research team cooperated with the Chen Xingqiu research group and Sun Dongming research group of the Institute of Metals, and found that the single-layer MoSi2N4 has semiconducting properties (band gap is about 1.94 eV) and theoretical carrier mobility better than MoS2, and shows excellent performance. Based on the mechanical strength and stability of single-layer semiconductor materials such as MoS2; theoretical calculations have predicted more than a dozen two-dimensional layered materials with the same structure as single-layer MoSi2N4, including semiconductors, metals and magnetic semi-metals with different band gaps.

This research has opened up a new family of two-dimensional layered MoSi2N4 materials, expanded the physical properties and applications of two-dimensional materials, and opened up the research direction of preparing new two-dimensional van der Waals layered materials, providing new opportunities for obtaining more new two-dimensional materials. Ideas.

The research work is funded by the National Natural Science Foundation of China's Outstanding Youth Science Fund, major projects, the original innovation project from 0 to 1 of the Chinese Academy of Sciences, the strategic leading science and technology project, and the national key research and development plan.