Ultra-high mechanical flexibility of 2D silicon telluride
Ultra-high mechanical flexibility of 2D silicon telluride
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DOI：
10.1063/1.5120533
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发表时间：
2020-01-13
影响因子：
4
通讯作者：
Shen, Xiao
中科院分区：
文献类型：
--
作者：
Bhattarai, Romakanta;Shen, Xiao
碲化硅（Si2Te3）是一种二维材料，具有独特的可变结构，其中硅原子形成Si-Si二聚体来填充Te层之间的“金属”位置。Si-Si二聚体有四种可能的取向：三种平面内方向和一种平面外方向。Si2Te3的结构可变性使其具有不同寻常的性能，特别是机械性能。利用第一性原理计算的结果，我们发现Si2Te3单层可以维持高达38%的单轴拉伸应变，是所有二维材料中最高的。高机械灵活性允许施加机械应变，以减少带隙1.5 eV。随着应变的增加，带隙经历了一种不寻常的间接-直接-间接-直接转变。单轴应变可以有效地控制Si-Si二聚体的取向，有利于实际应用。
Silicon telluride (Si2Te3) is a two-dimensional material with a unique variable structure where the silicon atoms form Si-Si dimers to fill the "metal" sites between the Te layers. The Si-Si dimers have four possible orientations: three in-plane and one out-of-the plane directions. The structural variability of Si2Te3 allows unusual properties, especially the mechanical properties. Using results from first-principles calculations, we show that the Si2Te3 monolayer can sustain a uniaxial tensile strain up to 38%, the highest among all two-dimensional materials reported. The high mechanical flexibility allows applying mechanical strain to reduce the bandgap by 1.5 eV. With increasing strain, the bandgap undergoes an unusual indirect-direct-indirect-direct transition. We also show that the uniaxial strain can effectively control the Si-Si dimer alignment, which is beneficial for practical applications.