Low-symmetry two-dimensional BNP\(_2\) and C\(_2\)SiS structures with high and anisotropic carrier mobilities

• Published in: arXiv.org
• Main Authors: Song, Shixin, Guan, Jie, Tománek, David
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 10.11.2020
• Subjects: Allotropy; Anisotropy; Density functional theory; Dimensional stability; Dynamic stability; Electronic structure; Energy gap; Molecular dynamics; Optoelectronics; Structural stability; Transport properties
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2011.04951

We study the stability and electronic structure of previously unexplored two-dimensional (2D) ternary compounds BNP\(_2\) and C\(_2\)SiS. Using \(ab\) \(initio\) density functional theory, we have identified four stable allotropes of each ternary compound and confirmed their stability by calculated phonon spectra and molecular dynamics simulations. Whereas all BNP\(_2\) allotropes are semiconducting, we find C\(_2\)SiS, depending on the allotrope, to be semiconducting or semimetallic. The fundamental band gaps of the semiconducting allotropes we study range from \(1.4\) eV to \(2.2\) eV at the HSE06 level \(0.5\) eV to \(1.4\) eV at the PBE level and display carrier mobilities as high as \(1.5{\times}10^5\) cm\(^2\)V\(^{-1}\)s\(^{-1}\). Such high mobilities are quite uncommon in semiconductors with so wide band gaps. Structural ridges in the geometry of all allotropes cause a high anisotropy in their mechanical and transport properties, promising a wide range of applications in electronics and optoelectronics.