China University of Science and Technology has made new progress in the study of two-dimensional material series

China University of Science and Technology has made new progress in the study of two-dimensional material series

The Morphology of Hemiphosphorus and Monolayer Blue Phosphorous on GaN (001) Surface and the Barrier to the Diffusion of Phosphorus Atoms at Its Surface and Interface

Recently, the International Functional Materials Quantum Design Center of the Hefei National Laboratory for Physical Sciences at the China National University of Science and Technology has made new progress in the study of two-dimensional material series. Theoretically, it is predicted that single-layer blue phosphors can be epitaxially grown on GaN (001) substrates. And proposed an unconventional "half-half layer" growth mechanism. The research results were published on the 27th of January in the "Physical Review Letters" of the International Physical Journal and were selected as editors' recommendations (Half Layer By Half Layer Growth of a Blue Phosphorene Monolayer on a GaN (001) Substrate). Editors' Suggestion). Doctor Zeng Zeng was the first author, and Cui Ping and Zhang Zhenyu were correspondence authors.

Two-dimensional materials have many superior physical and chemical properties. As Geim and Novoselov succeeded in mechanically stripping monolayer graphene in 2004, more and more condensed matter physics and materials science research is being carried out around different types of two-dimensional materials. A black-phosphorus single crystal with a two-dimensional layered structure similar to that of graphite thin was first obtained in 2014 by Chen Xianhui, a professor at China University of Science and Technology, and his collaborators through a mechanical stripping method. Due to its ultra-high carrier mobility and adjustable energy gap (direct bandgap), black phosphorus has a huge application prospect in the semiconductor industry and optical devices. The blue-phosphorus monoatomic layer as an allotrope of black phosphorus is also predicted to be stable. For practical applications, the preparation of high-quality two-dimensional black phosphorus or blue phosphorus single crystals based on epitaxial growth is a scientific research problem to be solved urgently.

In response to this challenge, the team found through first-principles calculations that due to the relatively flat structure of blue phosphorous, it is always more stable on the substrate than black phosphorus, and Au(111), Cu(111), and GaN ( 001) are substrates suitable for monolayer growth of blue phosphors. Moreover, because of the chemical affinity of the phosphorus element and the gallium element and better lattice matching, blue phosphorus is more stable on the GaN (001) surface, and this deduction is also verified by the first-principles molecular dynamics simulation. Through multi-scale growth kinetics simulations, the team also found that the growth of blue phosphorus on GaN (001) substrates follows a very large scale of “half-half layer” growth: when adsorbed phosphorus atoms are on the GaN (001) surface When the coverage is increased, the phosphorous atom will first form a relatively stable transition structure that is equivalent to the blue phosphor in the lower layer; as the coverage increases further, the blue phosphor in the upper layer also begins to form, eventually forming a stable blue. Phosphorus monolayer.

It is worth pointing out that this novel "half-half-layer" growth mechanism is fundamentally different from the dominant single-layer graphene epitaxial growth mechanism previously discovered by the team, effectively expanding people's diversity. The Cognition of Non-equilibrium Growth in the Van der Waals System. In addition, during the review of this work, experiments have been conducted to grow a nearly complete monolayer of blue phosphorus on an Au(111) substrate. On the semiconductor GaN (001) substrate, the blue phosphorous or blue phosphorous monolayer is grown. Because it can be directly used for device exploration, it has its more attractive basis and application prospects.

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