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arXiv · 1906.11601

Ultra-High Mechanical Flexibility of 2D Silicon Telluride

Romakanta Bhattarai·Xiao Shen
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Abstract

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%, highest among all two-dimensional materials reported. The high mechanical flexibility allows applying mechanical strain to reduce the band gap by 1.4 eV. With increasing strain, the band gap 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.

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Romakanta Bhattarai, Xiao Shen. 2019-06-27. Ultra-High Mechanical Flexibility of 2D Silicon Telluride. https://doi.org/10.1063/1.5120533

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