Fan Yingcai, Liu Xiaobiao, Wang Junru, Ai Haoqiang, Zhao Mingwen
Department of Assets Management, School of Information and Electronic Engineering, Shandong Technology and Business University, Yantai 264005, China.
Phys Chem Chem Phys. 2018 Apr 25;20(16):11369-11377. doi: 10.1039/c8cp00610e.
Using first-principles calculations, we show that the recently synthesized two-dimensional (2D) van der Waals layered material indium selenide (InSe) nanosheets can serve as a suitable substrate for silicene and germanene, which form commensurate and stable silicene/InSe (Si/InSe) and germanene/InSe (Ge/InSe) heterolayers (HLs). The buckled honeycomb geometries and Dirac-cone-like band structures of silicene and germanene are well preserved in these HLs. The interaction between silicene (or germanene) and the InSe substrate opens up a band gap of 141 meV (or 149 meV) at the Dirac points, while electron effective masses (EEM) remain as small as 0.059 and 0.067 times the free-electron mass (m0). The band gap and the EEM of the HLs can be further modulated effectively by applying an external electric field or strain. These features are attributed to the built-in electric field due to the interlayer charge transfer of the HLs which breaks the equivalence of the two sublattices of silicene and germanene. Multilayer (ML) InSe substrates have also been considered. We also proposed a parallel plate capacitor model to describe the interaction between silicene (or germanene) and the InSe substrate as well as the electronic band structure modification in response to an external field. This work is expected to offer an ideal substrate material for the growth of silicene and germanene and a promising van der Waals (vdW) layered heterostructure for electronic devices.
通过第一性原理计算，我们表明，最近合成的二维（2D）范德华层状材料硒化铟（InSe）纳米片可作为硅烯和锗烯的合适衬底，它们能形成匹配且稳定的硅烯/InSe（Si/InSe）和锗烯/InSe（Ge/InSe）异质层（HLs）。硅烯和锗烯的翘曲蜂窝状几何结构以及类似狄拉克锥的能带结构在这些异质层中得到了很好的保留。硅烯（或锗烯）与InSe衬底之间的相互作用在狄拉克点处打开了141毫电子伏特（或149毫电子伏特）的带隙，而电子有效质量（EEM）仍小至自由电子质量（m0）的0.059倍和0.067倍。通过施加外部电场或应变，可以进一步有效地调制异质层的带隙和EEM。这些特性归因于异质层的层间电荷转移所产生的内建电场，该电场打破了硅烯和锗烯两个子晶格的等效性。我们还考虑了多层（ML）InSe衬底。我们还提出了一个平行板电容器模型来描述硅烯（或锗烯）与InSe衬底之间的相互作用以及响应外部场时的电子能带结构变化。这项工作有望为硅烯和锗烯的生长提供一种理想的衬底材料，并为电子器件提供一种有前景的范德华（vdW）层状异质结构。
