Temperature Dependence of the Anisotropic Dielectric Properties of Semi-insulating -Ga₂O₃ in the Terahertz Region

We conducted measurements using terahertz time-domain spectroscopy on a semi-insulating bulk sample of (001)-oriented beta gallium oxide (beta-Ga2O3) in the temperature range of 90 K to 400 K. We analyzed the complex dielectric function parallel to the a-axis [100] and b-axis [010] in the frequency range from 0.2 to 3 THz using the Lorentz model. Our analysis enabled us to investigate the temperature dependence of the static dielectric constants and phonon absorption, as well as the anisotropy of beta-Ga2O3.