Litvinchuk Alexander P, Gavrilenko Vladimir I, Tang Zhongjia, Guloy Arnold M
Texas Center for Superconductivity and Department of Physics, University of Houston, Houston, TX 77204-5002, United States of America.
J Phys Condens Matter. 2019 Apr 3;31(13):135401. doi: 10.1088/1361-648X/aaffe9. Epub 2019 Jan 18.
Optical and vibrational properties of a novel allotrope of elemental germanium Ge(oP32), which crystallizes in the structure corresponding to the orthorhombic space group Pbcm, are studied experimentally by means of absorption and polarized Raman scattering measurements and theoretically using the first principles density functional theory. Material is found to be a direct band gap semiconductor with E = 0.33 eV. Out of theoretically predicted 48 Raman-active modes, 27 are observed in the spectra and assigned to the specific lattice eigenmodes of the crystal based on their symmetry and a comparison with the results of first principles lattice dynamics calculations. Remarkably, the highest frequency vibration is observed at 316 cm, that is higher than the cubic crystalline [Formula: see text]-Ge mode at 300 cm. Exceptional sharpness of observed phonon lines (between 0.8 and 2.5 cm at T = 10 K) implies excellent crystallinity of Ge(oP32) crystals.
通过吸收和偏振拉曼散射测量对一种新型元素锗同素异形体Ge(oP32)的光学和振动性质进行了实验研究，该同素异形体结晶于与正交空间群Pbcm相对应的结构中，并使用第一性原理密度泛函理论进行了理论研究。发现该材料是一种直接带隙半导体，其E = 0.33 eV。在理论预测的48个拉曼活性模式中，在光谱中观察到27个，并根据它们的对称性以及与第一性原理晶格动力学计算结果的比较，将其分配给晶体的特定晶格本征模式。值得注意的是，观察到的最高频率振动出现在316 cm处，高于立方晶体[公式：见正文]-Ge模式的300 cm。观察到的声子线异常尖锐（在T = 10 K时为0.8至2.5 cm之间）意味着Ge(oP32)晶体具有优异的结晶度。
