二维半导体SeSC₂晶体结构、稳定性和物理性质的理论研究

Theoretical Study on Crystal Structure, Stability and Physical Properties of Two-Dimensional Semiconductor SeSC₂

摘要: 新型二维晶体及其新特性为纳米电子器件的发展提供了动力，因此寻找它们是一项持续的基础研究重点。通过第一性原理计算发现，二维三元材料SeSC₂是一种稳定的间接带隙半导体，其带隙宽度为2.43 eV。声子谱和分子动力学模拟等结果证实了其优异的稳定性。通过施加−3%~3%的双轴应力，其电子能带结构可在0.78~3.09 eV范围内调节。化学修饰也是改变SeSC₂薄膜能带结构的有效方法，氢化、氟化和氯化处理的SeSC₂薄膜分别具有3.49 eV、2.57 eV和1.89 eV的间接带隙。此外，三元SeSC₂薄膜和化学修饰的SeSC₂薄膜展现出新颖的光学特性。这些独特性质有望在未来纳米光电领域获得应用。

Abstract: Novel two-dimensional crystals and their new properties provide impetus for the development of nanoelectronic devices, therefore, the search for them is a fundamental ongoing research focus. Here, the two-dimensional ternary material SeSC₂ was found to be a stable semiconductor with an indirect band gap of 2.43eV by first principle calculation. Its excellent stability is confirmed through the phonon spectrum and molecular dynamics simulation, etc. Through applying external small biaxial strain (−3%~3%), its electronic band structure can be tuned in the range of 0.78~3.09 eV. Chemical modification is also a useful method to change the band structure of the SeSC₂ sheet. The hydrogenated, fluoridated, and chlorinated SeSC₂ sheets are found to have indirect band gaps of 3.49 eV, 2.57 eV and 1.89 eV, respectively. Moreover, the ternary SeSC₂ sheet and chemically modified SeSC₂ sheets exhibit novel optical properties. These unique properties are promising for applications in future nano-optoelectronic fields.