Department of Physics, Materials Genome Institute, and International Centre for Quantum and Molecular Structures, Shanghai University, 99 Shangda Road, Shanghai, 200444, P.R. China.
Department of Materials Physics and Chemistry, School of Materials Science and Engineering, and Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, No. 3-11 Wenhua Road, Shenyang, 110819, P.R. China.
Sci Rep. 2017 Sep 5;7(1):10546. doi: 10.1038/s41598-017-10670-x.
Compared to the pure two-dimensional (2D) graphene and silicene, the binary 2D system silagraphenes, consisting of both C and Si atoms, possess more diverse electronic structures depending on their various chemical stoichiometry and arrangement pattern of binary components. By performing calculations with both density functional theory and a Tight-binding model, we elucidated the formation of Dirac cone (DC) band structures in SiC and SiC as well as their analogous binary monolayers including SiGe, SiGe, GeC, and GeC. A "ring coupling" mechanism, referring to the couplings among the six ring atoms, was proposed to explain the origin of DCs in AB and AB binary systems, based on which we discussed the methods tuning the SiC systems into self-doped systems. The first-principles quantum transport calculations by non-equilibrium Green's function method combined with density functional theory showed that the electron conductance of SiC and SiC lie between those of graphene and silicene, proportional to the carbon concentrations. Understanding the DC formation mechanism and electronic properties sheds light onto the design principles for novel Fermi Dirac systems used in nanoelectronic devices.
与纯二维（2D）石墨烯和硅烯相比，由 C 和 Si 原子组成的二元 2D 系统硅烯具有更多样的电子结构，这取决于它们不同的化学计量和二元成分的排列模式。通过密度泛函理论和紧束缚模型的计算，我们阐明了在 SiC 和 SiC 以及它们类似的二元单层材料（包括 SiGe、SiGe、GeC 和 GeC）中形成的狄拉克锥（DC）能带结构。提出了一种“环耦合”机制，即六个环原子之间的耦合，用于解释 AB 和 AB 二元体系中 DC 的起源，在此基础上，我们讨论了将 SiC 体系调谐为自掺杂体系的方法。基于密度泛函理论的非平衡格林函数方法的第一性原理量子输运计算表明，SiC 和 SiC 的电子电导介于石墨烯和硅烯之间，与碳浓度成正比。理解 DC 的形成机制和电子特性为用于纳米电子器件的新型费米狄拉克系统的设计原则提供了启示。
