Abstract

Monolayer silicene and germanene have received intensive attention due to their good compatibility with current Si-based electronics. However, the lack of a bandgap severely limits their applications in complex electronic circuits. To overcome this obstacle, we build Si_1−xGe_x superlattices (SLs) and further cleave them into nanoribbons to tune the electrical properties of silicene and germanene, and analyze their transport behavior by means of density functional theory combined with the nonequilibrium Green’s function formalism. Among all the designed Si_1−xGe_x SLs, Si_0.5Ge_0.5 possesses the widest bandgap of 0.53 eV, as its larger amount of Ge–Si bonds can result in strong absorption of light towards short wavelengths. By edge functionalization with Li, H, and F atoms, the conduction type of the monolayer Si_0.5Ge_0.5 nanoribbons can be rationally tuned from n-type to ambipolar to p-type. These tunable electronic properties can be attributed to the internal and interfacial charge transfer. The simulated transport behavior of field-effect transistors based on monolayer Si_0.5Ge_0.5 nanoribbons demonstrates that such edge functionalization could be applied to modulate the conductivity, conduction type, on/off ratio, and carrier concentration effectively. The results of this work reveal the great potential of edge functionalization for tuning the electrical properties of two-dimensional (2D) semiconductors.

Graphic abstract

中文翻译：

---

边缘功能化对单层Si 0.5 Ge 0.5纳米带晶体管器件性能的影响

摘要

单层硅烯和锗烯由于与当前基于硅的电子产品良好的兼容性而受到广泛关注。然而，带隙的缺乏严重限制了它们在复杂电子电路中的应用。为了克服这一障碍，我们建立了Si _{1− x} Ge _x超晶格（SLs），然后将其切割成纳米带，以调节硅和锗的电性能，并通过密度泛函理论和非平衡格林函数分析了它们的传输行为。形式主义。在所有设计的Si _{1- x} Ge _x SLs中，Si _0.5 Ge _0.5具有0.53 eV的最宽带隙，因为其较大数量的Ge-Si键可以导致短波长的光强吸收。通过用Li，H和F原子进行边缘官能化，可以合理地将单层Si _0.5 Ge _0.5纳米带的导电类型从n型变为双极性，再到p型。这些可调节的电子特性可归因于内部和界面电荷转移。基于单层Si _0.5 Ge _0.5的场效应晶体管的模拟传输行为纳米带证明了这种边缘功能化可以有效地调节电导率，导电类型，开/关比和载流子浓度。这项工作的结果表明，边缘功能化对于调整二维（2D）半导体的电性能具有巨大的潜力。

图形摘要