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image of Strain-dependent Electronic and Optical Properties of Bulk and 
Monolayer β-GeX2 (X = S, Se)

Abstract

Introduction

Monoclinic β-GeSe exhibits strong in-plane anisotropy, a wide direct bandgap, and strain-tunable properties, making it a promising material for ultraviolet photodetection and optoelectronic applications. This mini-review examines the strain engineering of β-GeX (X = S, Se), with a focus on its electronic and optical properties.

Methods

Density functional theory (DFT) calculations provide insights into the structural, electronic, and optical characteristics of bulk and monolayer β-GeX. The impact of biaxial strain on the band structure, dielectric function, absorption, and refractive index is examined.

Results

Tensile strain narrows the bandgap in monolayer β-GeX, while compressive strain induces a direct-to-indirect transition. The static dielectric constant ε(0) ranges from 2.16 (compressive) to 4.65 (tensile), with the absorption peak shifting from 6.25 eV (compressive) to 7.07 eV (tensile). The refractive index n(0) extends from 1.47 to 2.15, while the plasma frequency ω shifts between 7.33 eV (compressive) and 8.91 eV (tensile). These findings are discussed with respect to current and future applications in optoelectronic devices.

Discussion

Strain engineering in monolayer β-GeX offers a powerful tool to modulate its properties for next-generation optoelectronics. Further experimental research is needed to fully explore the capabilities of strain-engineered β-GeX materials for advanced devices.

Conclusion

Strain engineering enhances the tunability of β-GeX properties, demonstrating promising potential for optoelectronic applications. This study summarizes key findings and encourages further research, including the investigation of strain effects in other novel 2D materials to enhance device performance.

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2025-09-02
2025-11-16

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Strain-dependent Electronic and Optical Properties of Bulk and 
Monolayer β-GeX2 (X = S, Se)
Bentham Science Publishers ; https://doi.org/10.2174/0126661454384578250825055630
/content/journals/cms/10.2174/0126661454384578250825055630
/content/journals/cms/10.2174/0126661454384578250825055630
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  • Article Type:     Review Article
Keywords: strain ; chemical vapor transport (CVT) ; single X-ray diffraction ; density functional theory (DFT) ; Monolayer ; β-GeX2

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