太赫兹波段碲化镉介电常数的理论与实验研究

该文采用密度泛函理论研究了闪锌矿型碲化镉的声子色散谱、特征向量及晶格振动频率，获得了碲化镉介电常数随频率变化的理论值。通过太赫兹时域光谱系统测量碲化镉单晶的介电常数，该实验结果与局域密度近似修正、广义梯度近似修正和广义梯度近似修正的计算结果吻合较好。最后，3种近似交换关联势的计算结果之间存在一定差异性，该差异性结果表明太赫兹波段碲化镉的介电常数由电子声子耦合所主导，但是横波和纵波声子频率敏感于电子密度分布。 

Theoretical and Experimental Study on the Permittivity of CdTe in the Terahertz Band

The phonon dispersion spectrum, eigenvector, and lattice vibration frequency of cadmium telluride with a zinc blende structure have been investigated using the density functional theory, and the permittivity of cadmium telluride crystal is numerically calculated. The permittivity of the crystal is measured using the terahertz time-domain spectroscopy system. The experimental results are consistent with the theoretical calculations on the modified local density approximation, the general gradient approximation, and the modified general gradient approximation. Finally, the differences among the three approximate exchange correlation potentials indicate that in the terahertz region, the permittivity of cadmium telluride is dominantly contributed by the coupling between electron and phonon; however, the phonon frequencies of transverse wave and longitudinal wave were sensitive to electron density distribution.