Helium incorporation induced direct-gap silicides
Abstract The search of direct-gap Si-based semiconductors is of great interest due to the potential application in many technologically relevant fields. This work examines the incorporation of He as a possible route to form a direct band gap in Si. Structure predictions and first-principles calculat...
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| Autores principales: | , , , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Nature Portfolio
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/0b6fea9a18ad4c769b42bf3c9ded63ae |
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| Sumario: | Abstract The search of direct-gap Si-based semiconductors is of great interest due to the potential application in many technologically relevant fields. This work examines the incorporation of He as a possible route to form a direct band gap in Si. Structure predictions and first-principles calculations show that He and Si, at high pressure, form four dynamically stable phases of Si2He (oP36-Si2He, tP9-Si2He, mC18-Si2He, and mC12-Si2He). All phases adopt host–guest structures consisting of a channel-like Si host framework filled with He guest atoms. The Si frameworks in oP36-Si2He, tP9-Si2He, and mC12-Si2He could be retained to ambient pressure after removal of He, forming three pure Si allotropes. Among them, oP36-Si2He and mC12-Si2He exhibit direct band gaps of 1.24 and 1.34 eV, respectively, close to the optimal value (~1.3 eV) for solar cell applications. Analysis shows that mC12-Si2He with an electric dipole transition allowed band gap possesses higher absorption capacity than cubic diamond Si, which makes it to be a promising candidate material for thin-film solar cell. |
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