Shi Bowen, Tang Hao, Song Zhigang, Li Jingzhen, Xu Lianqiang, Liu Shiqi, Yang Jie, Sun Xiaotian, Quhe Ruge, Yang Jinbo, Lu Jing
State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, P. R. China.
Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Nanoscale. 2021 Sep 17;13(35):15048-15057. doi: 10.1039/d1nr02221k.
Recently, a topological-to-trivial insulator quantum-phase transition induced by an electric field has been experimentally reported in monolayer (ML) and bilayer (BL) NaBi. A narrow ML/BL NaBi nanoribbon is necessary to fabricate a high-performance topological transistor. By using the density functional theory method, we found that wider ML NaBi nanoribbons (>7 nm) are topological insulators, featured by insulating bulk states and dissipationless metallic edge states. However, a bandgap is opened for extremely narrow ML NaBi nanoribbons (<4 nm) due to the quantum confinement effect, and its size increases with the decrease in width. In the topological insulating ML NaBi nanoribbons, a bandgap is opened in the metallic edge states under an external displacement electric field, with strength (∼1.0 V Å) much smaller than the reopened displacement electric field in ML NaBi (3 V Å). An ultrashort ML NaBi zigzag nanoribbon topological transistor switched by the electrical field was calculated using first-principles quantum transport simulation. It shows an on/off current/conductance ratio of 4-71 and a large on-state current of 1090 μA μm. Therefore, a proof of the concept of topological transistors is presented.
最近，实验报道了在单层（ML）和双层（BL）NaBi中由电场诱导的拓扑到平凡绝缘体的量子相变。制造高性能拓扑晶体管需要一条窄的ML/BL NaBi纳米带。通过使用密度泛函理论方法，我们发现更宽的ML NaBi纳米带（>7 nm）是拓扑绝缘体，其特征是具有绝缘的体态和无耗散的金属边缘态。然而，由于量子限制效应，极窄的ML NaBi纳米带（<4 nm）会打开一个带隙，并且其大小随着宽度的减小而增加。在拓扑绝缘的ML NaBi纳米带中，在外部位移电场下金属边缘态会打开一个带隙，其强度（~1.0 V Å）远小于ML NaBi中重新打开的位移电场（3 V Å）。使用第一性原理量子输运模拟计算了由电场切换的超短ML NaBi锯齿形纳米带拓扑晶体管。它显示出4 - 71的开/关电流/电导比和1090 μA μm的大导通态电流。因此，提出了拓扑晶体管概念的证明。
