For very few special 2D materials, electric field can be used to realize the topological phase transition from normal insulator (NI) into topological insulator (TI). To design the low-power electronic devices based on 2DTIs, tunable and practical 2DTIs may be necessary. Herein, a model of electric field-tunable 2DTIs based on bilayer van der Waals semiconductors is proposed. The bilayer semiconductors can be tuned by electric field from NIs into TIs. As a good candidate of the predicted 2DTIs, the possible topological phase transition of bilayer stanane (SnH) under electric field using first-principles calculations is studied. The calculations suggest that bilayer stanane can be converted from NI into TI by vertical electric field. The topological bandgap can be up to about 22.8 meV, which is giant for the electric field-tunable 2DTIs. It can be further enlarged by vertical pressure. This discovery provides new possibilities for converting NIs into TIs by electric field and creating multifunctional topological field-effect transistors by tunable 2DTIs.

中文翻译：

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通过电场调节双层范德华斯坦烷中的带隙和拓扑相变

对于极少数特殊二维材料，可以利用电场实现从普通绝缘体（NI）到拓扑绝缘体（TI）的拓扑相变。为了设计基于 2DTI 的低功耗电子设备，可能需要可调谐且实用的 2DTI。本文提出了一种基于双层范德华半导体的电场可调 2DTI 模型。双层半导体可以通过电场从 NI 调谐到 TI。作为预测 2DTI 的良好候选者，我们使用第一原理计算研究了电场下双层锡烷 (SnH) 可能的拓扑相变。计算表明，双层锡烷可以通过垂直电场从NI转化为TI。拓扑带隙可达约 22.8 meV，这对于电场可调谐 2DTI 来说是巨大的。可以通过垂直压力进一步放大。这一发现为通过电场将NI转换为TI以及通过可调谐2DTI创建多功能拓扑场效应晶体管提供了新的可能性。