A silicon allotrope which consists of 24 atoms in a body centered cubic cell and displays an symmetry (termed as cI24‐Si) with a mass density of 2.38 g/cm³, is theoretically investigated. This silicon phase has an all‐sp³ network with hexagons. Phonon dispersion confirms its dynamical stability and elastic constant implies it is mechanically stable. The analysis of electronic band structure performing by HSE06 functional shows that cI24‐Si is an indirect semiconductor with a small band gap of 0.83 eV. Additionally, its direct band gap is only 0.02 eV larger than the indirect band gap, indicating that cI24‐Si possesses a quasi‐direct band gap. The calculations of imaginary part of dielectric function and optical absorption for cI24‐Si show that it has better optical properties than diamond‐like Si−I phase as it can capture more sunlight from visible to ultraviolet range. To provide more characterizations for future experimental observations, X‐ray diffraction patterns and Raman spectra are also theoretically simulated. Due to its small band gap, cI24‐Si may possess potential electronic, optical and photovoltaic applications.

中文翻译：

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CI24-Si：具有All-sp3键合网络的半导体硅相

在理论上研究了一种硅同素异形体，它由24个原子组成，位于一个体心立方单元中，并且显示出对称性（称为cI 24-Si），质量密度为2.38 g / cm ³。该硅相具有六边形的全sp ³网络。声子分散证实了它的动态稳定性，而弹性常数表明它在机械上是稳定的。对通过HSE06功能执行的电子带结构的分析表明，cI 24-Si是一种间接半导体，其带隙为0.83 eV。此外，其直接带隙仅比间接带隙大0.02 eV，表明cI24-Si具有准直接带隙。对cI 24-Si的介电函数和光吸收的虚部的计算表明，它具有比类金刚石Si-I相更好的光学性能，因为它可以捕获更多可见光到紫外线范围的阳光。为了为将来的实验观察提供更多的特征，在理论上还模拟了X射线衍射图和拉曼光谱。由于带隙很小，cI 24‐Si可能具有潜在的电子，光学和光伏应用。