Bafekry Asadollah, Shahrokhi Masoud, Shafique Aamir, Jappor Hamad R, Fadlallah Mohamed M, Stampfl Catherine, Ghergherehchi Mitra, Mushtaq Muhammad, Feghhi Seyed Amir Hossein, Gogova Daniela
Department of Radiation Application, Shahid Beheshti University, 19839 69411 Tehran, Iran.
Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
ACS Omega. 2021 Mar 30;6(14):9433-9441. doi: 10.1021/acsomega.0c06024. eCollection 2021 Apr 13.
Very recently, a new class of the multicationic and -anionic entropy-stabilized chalcogenide alloys based on the (Ge, Sn, Pb) (S, Se, Te) formula has been successfully fabricated and characterized experimentally [Zihao Deng , 6070 ()]. Motivated by the recent experiment, herein, we perform density functional theory-based first-principles calculations in order to investigate the structural, mechanical, electronic, optical, and thermoelectric properties. The calculations of the cohesive energy and elasticity parameters indicate that the alloy is stable. Also, the mechanical study shows that the alloy has a brittle nature. The GeSnPbSSeTe alloy is a semiconductor with a direct band gap of 0.4 eV (0.3 eV using spin-orbit coupling effect). The optical analysis illustrates that the first peak of Im(ε) for the GeSnPbSSeTe alloy along all polarization directions is located in the visible range of the spectrum which renders it a promising material for applications in optical and electronic devices. Interestingly, we find an optically anisotropic character of this system which is highly desirable for the design of polarization-sensitive photodetectors. We have accurately predicted the thermoelectric coefficients and have calculated a large power factor value of 3.7 × 10 W m K s for p-type. The high p-type power factor is originated from the multiple valleys near the valence band maxima. The anisotropic results of the optical and transport properties are related to the specific tetragonal alloy unit cell.
最近，一类基于(Ge, Sn, Pb)(S, Se, Te)化学式的新型多阳离子和多阴离子熵稳定硫族化物合金已成功制备并通过实验表征[邓子豪, 6070 ()]。受近期实验的启发，在此我们进行基于密度泛函理论的第一性原理计算，以研究其结构、力学、电子、光学和热电性质。结合能和弹性参数的计算表明该合金是稳定的。此外，力学研究表明该合金具有脆性。GeSnPbSSeTe合金是一种半导体，直接带隙为0.4 eV（考虑自旋轨道耦合效应时为0.3 eV）。光学分析表明，GeSnPbSSeTe合金在所有极化方向上Im(ε)的第一个峰值位于光谱的可见光范围内，这使其成为光学和电子器件应用的有前景材料。有趣的是，我们发现该体系具有光学各向异性特征，这对于偏振敏感光电探测器的设计非常理想。我们准确预测了热电系数，并计算出p型的大功率因子值为3.7×10 W m K s 。高p型功率因子源于价带最大值附近的多个谷。光学和输运性质的各向异性结果与特定的四方合金晶胞有关。
