硅基Ⅳ族SiGeSn三元合金晶格结构、电子结构和光学性质的第一性原理

摘要/Abstract

摘要： SiGeSn三元合金由于具有较二元合金更大的晶格和能带性质调控范围,是当前用于制作硅基激光器的热点材料。为全面且精确地研究其晶格结构、电子结构和光学性质,本文采用基于密度泛函理论(DFT)的第一性原理方法,并结合准随机近似和杂化泛函带隙修正,首先研究SiGeSn晶格常数及其弯曲系数的变化规律,并给出了解决GeSn二元晶格失配和压应变问题的方案。其次比较研究了SiGeSn与GeSn合金的能带结构,并通过态密度计算分析了Si的引入对合金带隙变化的物理机制。最后比较研究了SiGeSn与GeSn合金的介电函数谱、吸收系数、消光系数、反射率、折射率和发射率等光学性质。结果表明,SiGeSn晶格常数弯曲系数的变化与合金电负性差值的变化规律一致,Si-p电子态是SiGeSn合金带隙变化的最主要贡献。相比于同Sn浓度的GeSn合金,SiGeSn能保持直接带隙特征,且其带隙值和光吸收波长呈现更宽的变化范围。因此在拓宽硅基高效光源和光电探测器应用波段方面,SiGeSn相较于GeSn合金具有更大的应用潜力和优势。

关键词: SiGeSn三元合金, 晶格结构, 电子结构, 光学性质, 第一性原理计算

Abstract: SiGeSn ternary alloys are hot materials for making silicon-based lasers currently due to their larger lattice and bandgap variation range compared with Group-Ⅳ binary alloys. In this paper, the first-principles methods based on density functional theory (DFT) were used to comprehensively and accurately study the lattice structure, electronic structure and optical properties of SiGeSn. Combined with quasi-random approximation and hybrid functional band gap correction, the lattice constants, band structure, density of states and optical properties of Si_1-x-yGe_xSn_y with different concentrations were calculated. Firstly, the variation law of lattice constant and bowing factor of SiGeSn were studied, and the solving schemes for the problems caused by mismatch and compressive strains for GeSn binary alloys were provided. Secondly, the band structures of SiGeSn and GeSn alloys were comparatively studied, and the microscopic mechanism of the effects on bandgap when alloying Si in GeSn was analyzed. Finally, the optical properties of SiGeSn and GeSn alloys such as dielectric function spectrum, absorption coefficient, extinction coefficient, reflectivity, refractive index and emissivity were comparatively studied. The results show the variation law of the lattice constant bowing factor is consistent with that of the electronegativity difference for SiGeSn, and Si-p electronic state is the most important contribution to the change of band gap. Compared to GeSn alloy with the same Sn concentration, SiGeSn can maintain the direct band gap characteristics and its band gap and light absorption wavelength have a wider variation range. Therefore, compared with GeSn alloy, SiGeSn has greater potential and advantages in the field of broadening the application wavelength of silicon-based high-efficiency light sources and photodetectors.

Key words: SiGeSn ternary alloy, lattice structure, band structure, optical property, first-principle calculation

中图分类号:

TG131
O469

孙生柳, 黄文奇, 张立鑫, 谌珍雨, 王浩. 硅基Ⅳ族SiGeSn三元合金晶格结构、电子结构和光学性质的第一性原理[J]. 人工晶体学报, 2021, 50(12): 2232-2239.

SUN Shengliu, HUANG Wenqi, ZHANG Lixin, CHEN Zhenyu, WANG Hao. First-Principles Study on Lattice Structure, Electronic Structure and Optical Properties of Group-Ⅳ SiGeSn Ternary Alloy[J]. JOURNAL OF SYNTHETIC CRYSTALS, 2021, 50(12): 2232-2239.

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