Optical and Dielectric Properties of ZnO Nanostructures at Terahertz Frequencies

Abstract

The purpose of this study is to characterize the optical and dielectric properties of the nanostructures of ZnO in the far infrared regime using THz time-domain spectroscopy. The experimentally obtained frequency dependent refractive indices, power absorptions and complex dielectric constants for nanowires and tetrapods were theoretically fit by using a simple mixing model in tandem with classical pseudo-harmonic model. The experimentally obtained results of refractive indices, power absorption coefficients and complex dielectric functions fit well using the theoretical approach. The fitting revealed the presence of dominant TO-phonon mode centered at 12.41 THz for both the samples. Very similar THz spectra of the characterized nanostructures with that of the bulk allowed us to conclude that these nanostructures have similar crystal structure of bulk ZnO.