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首页> 外文期刊>Physica status solidi, B. Basic research >Lattice Dynamics and Bond Polarity of Be-Chalcogenides A New Class of II-VI Materials
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Lattice Dynamics and Bond Polarity of Be-Chalcogenides A New Class of II-VI Materials

机译：Be-硫族化物新型II-VI族材料的晶格动力学和键极性

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摘要

Be-chalcogenides take a special place among II-VI compounds due to their expected reduced polarity. We report on an investigation of the phonon properties and dielectric constants of BeSe and BeTe by far- and mid-infrared reflectance and Raman spectroscopy. For comparison with our experimental results we performed first-principles calculations (LDA) to obtain the charge distribution and the TO-phonon frequencies within the frozen phonon approximation. From the spectroscopic data we derive bond polarities, which are distinctly reduced with respect to classical II-VI compounds (ZnTe, ZnSe). They approach values of III-V compounds, such as GaAs. These results are also reflected in the calculated charge distributions. The least polar compound BeTe exhibits a very high frequency and narrow optical phonon band due to the extraordinary mass ratio m_(Be) = 9.0 amu versus m_(Te) = 127.6 amu. Therefore, in BeTe, in contrast to almost all other II-VI compounds, the standard optical phonon decay channel into two acoustic phonons with opposite momenta is not possible. We investigated the consequences for the temperature behaviour of the optical phonon parameters.
机译：硫属化物由于其预期的降低的极性而在II-VI化合物中占有特殊的位置。我们报告了通过远中红外反射率和拉曼光谱对BeSe和BeTe的声子性质和介电常数进行的研究。为了与我们的实验结果进行比较，我们进行了第一性原理计算（LDA），以获得冻结声子近似值内的电荷分布和TO声子频率。从光谱数据中我们得出键极性，相对于经典的II-VI化合物（ZnTe，ZnSe）明显减小。它们接近III-V化合物（例如GaAs）的值。这些结果也反映在计算的电荷分布中。由于非同寻常的质量比m_（Be）= 9.0 amu与m_（Te）= 127.6 amu，最弱极性的化合物BeTe表现出非常高的频率和较窄的光学声子带。因此，在BeTe中，与几乎所有其他II-VI化合物相反，标准光学声子衰减通道不可能变成具有相反动量的两个声子。我们研究了光子声子参数对温度行为的影响。

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