Terahertz dielectric properties of high-resistivity single-crystal ZnO

We present experimental characterization of complex dielectric properties of high-resistivity single-crystal ZnO by terahertz time-domain spectroscopy in the frequency range extending from 0.3to3.5THz. The measured refractive index, power absorption, and dielectric function are well fit by the pseudo-harmonic model of dielectric response. In addition, from the extrapolation of the experimental results, we show that the absorption is dominated by the transverse optical (TO) E1 phonon mode centered at frequency (ωTO∕2π) 12.42THz.