Prediction of Two-Dimensional Group IV Nitrides AxNy (A = Sn, Ge, or Si): Diverse Stoichiometric Ratios, Ferromagnetism, and Auxetic Mechanical Property

Heng Zhang; Junjie Wang; Frédéric Guégan; Gilles Frapper

doi:10.1021/acs.jpclett.2c02376

Prediction of Two-Dimensional Group IV Nitrides A_xN_y (A = Sn, Ge, or Si): Diverse Stoichiometric Ratios, Ferromagnetism, and Auxetic Mechanical Property

J Phys Chem Lett. 2022 Oct 13;13(40):9316-9325. doi: 10.1021/acs.jpclett.2c02376. Epub 2022 Sep 30.

Authors

Heng Zhang^{1

2}, Junjie Wang¹, Frédéric Guégan², Gilles Frapper^{1

2}

Affiliations

¹ State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, People's Republic of China.
² Applied Quantum Chemistry group, E4, IC2MP, UMR 7285 Poitiers University-CNRS, 4 rue Michel Brunet TSA, 51106, 86073 Poitiers Cedex 9, France.

PMID: 36178176
DOI: 10.1021/acs.jpclett.2c02376

Abstract

In this work, we unveiled a new class of two-dimensional (2D) group IV nitride A_xN_y (A = Sn, Ge, or Si) prototypes, C2/m A₄N, P3̅m1 A₃N, P3m1 A₂N, P3̅m1 A₃N₂, P6̅m2 AN, P3̅m1 AN, P6̅2m A₃N₄, P3m1 A₂N₃, P4̅2₁m AN₂, and P3̅m1 AN₃, by using evolutionary algorithms combined with first-principles calculations. Using HSE06 functional calculations, a wide range of band gaps from metal to semiconductor (0.405-5.050 eV) and ultrahigh carrier mobilities (1-24 × 10³ cm² V^-1 s^-1) were evidenced in these 2D structures. We found that 2D P3m1 Sn₂N₃, Ge₂N₃, and Si₂N₃ are intrinsic ferromagnetic semiconductors with gaps of 0.677, 1.285, and 2.321 eV, respectively. The lattice symmetry and Si-to-N₂ charge transfer upon strain lead to large anisotropic negative Poisson's ratios (-0.281 to -0.146) along whole in-plane directions in 2D P4̅2₁m SiN₂. Our findings not only enrich the family of 2D nitrides but also highlight the promising optoelectronic and nanoauxetic applications of 2D group IV nitrides.