Ultra-high mechanical flexibility of 2D silicon telluride

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 va...

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Bibliographic Details
Published in:Applied physics letters 2020-01, Vol.116 (2)
Main Authors: Bhattarai, Romakanta, Shen, Xiao
Format: Article
Language:English
Subjects:
Applied physics
Dimers
Energy gap
First principles
Flexibility
Intermetallic compounds
Mechanical properties
Molecular structure
Silicon
Tellurides
Tensile strain
Two dimensional materials
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Summary: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.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.5120533