Theoretical and Experimental Study on Dielectric Constant of Cadmium Telluride in Terahertz Band.

The phonon dispersion spectrum, eigenvector and lattice vibration frequency of zincblende cadmium telluride (CdTe) are studied by density functional theory (DFT). The vertical or parallel relationship between the phonon propagating wave vector atomic vibration direction is analyzed, and the frequency of the CdTe transverse (TO)/longitudinal (LO) optical phonon is obtained. The Boltzmann transport equation clearly expresses the phonon scattering process, which is combined with the Huang Kun equation to obtain the three-phonon collision frequency (γ). The terahertz time-domain spectroscopy system is used to measure the reflectivity and dielectric constant of CdTe single crystal. The experimental results verify that the theoretical calculation based on DFT can give the correct terahertz band dielectric constant with frequency dependence characteristics completely independent of the experiment. [ABSTRACT FROM AUTHOR]