Optical parameters of ZnTe determined using continuous-wave terahertz radiation

The optical parameters of three ZnTe crystal wafers of different thicknesses were determined using transmittance measurements of continuous-wave terahertz radiation from a two-color photomixing source. The parameters are extracted by fitting the transmittance data with theoretical curves generated using a Drude-Lorentz dielectric model of the crystal and a bootstrap statistical analysis of the fits. It was found at room temperature that the low and high frequency dielectric constants are ϵ(0) = 9.8±0.2 and ϵ(∞) = 7.3±0.6, respectively. The transverse optical phonon frequency was found to be νTO = 6.0±1.3 THz. Sample specific properties such as the plasma, collision, and phonon damping frequencies were determined and used for an approximate calculation of carrier concentration. The results are compared with a comprehensive review of earlier values from the literature. Our results are consistent with previous work, falling within the spread of accepted values, and demonstrate that this method is particularly suited for determining the low and high frequency dielectric constants of semiconductor samples.