TO ₁ soft mode in Fe doped β-Ga ₂O ₃ studied by terahertz time-domain spectroscopy

Abstract

The transmission spectra of terahertz (THz) waves through Fe doped β-Ga ₂O ₃ in the range of 1–6 THz by air-plasma-based THz time-domain spectroscopy (THz-TDS) at room temperature and their temperature dependence between 90 and 500 K in the range of 0.7 THz-1.8 THz have been measured. We estimated the complex dielectric constants by fitting the spectra with the classical damped oscillator dispersion model and obtained the anisotropic lowest transverse optical (TO ₁) phonon frequencies. The values at room temperature agreed with the reported values, and no significant temperature dependence was observed.