Department of Physics, University of Guilan, 41335-1914 Rasht, Iran.
Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
Phys Chem Chem Phys. 2019 Oct 7;21(37):21070-21083. doi: 10.1039/c9cp03853a. Epub 2019 Sep 17.
Using first-principles calculations the effect of topological defects, vacancies, Stone-Wales and anti-site and substitution of atoms, on the structure and electronic properties of monolayer CN are investigated. Vacancy defects introduce localized states near the Fermi level and a local magnetic moment. While pristine CN is an indirect semiconductor with a 0.4 eV band gap, with substitution of O, S and Si atoms for C, it remains a semiconductor with a band gap in the range 0.25-0.75 eV, while it turns into a metal with H, Cl, B, P, Li, Na, K, Be and Mg substitution. With F substitution, it becomes a dilute-magnetic semiconductor, while with Ca substitution it is a ferromagnetic-metal. When replacing the N host atom, CN turns into: a metal (H, O, S, C, Si, P, Li and Be), ferromagnetic-metal (Mg), half-metal (Ca) and spin-glass semiconductor (Na and K). Moreover, the effects of charging and strain on the electronic properties of Na atom substitution in CN are investigated. We found that the magnetic moment decreases or increases depending on the type and size of strain (tensile or compression). Our study shows how the band gap and magnetism in monolayer CN can be tuned by introducing defects and atom substitution. The so engineered CN can be a good candidate for future low dimensional devices.
采用第一性原理计算研究了拓扑缺陷、空位、Stone-Wales 和反位以及原子取代对单层 CN 的结构和电子性质的影响。空位缺陷在费米能级附近引入局域态和局部磁矩。而原始的 CN 是间接半导体，带隙为 0.4eV，而用 O、S 和 Si 原子取代 C 后，它仍然是带隙在 0.25-0.75eV 范围内的半导体，而用 H、Cl、B、P、Li、Na、K、Be 和 Mg 取代则变成金属。用 F 取代，它变成稀磁半导体，而用 Ca 取代则变成铁磁金属。当取代 N 主原子时，CN 变成：金属（H、O、S、C、Si、P、Li 和 Be）、铁磁金属（Mg）、半金属（Ca）和自旋玻璃半导体（Na 和 K）。此外，还研究了充电和应变对 CN 中 Na 原子取代的电子性质的影响。我们发现磁矩取决于应变的类型和大小（拉伸或压缩）而减小或增大。我们的研究表明，通过引入缺陷和原子取代可以调整单层 CN 的带隙和磁性。因此设计的 CN 可以成为未来低维器件的良好候选材料。
