Polar phonons in β-Ga2O3 studied by IR reflectance spectroscopy and first-principle calculations

Abstract

IR reflectance spectra of β-Ga2O3 are measured in the range from 400 to 1100 cm−1 using the and (010) planes for pure transverse Au- and Bu-mode phonons, respectively. The spectra measured using the (010) plane depend remarkably on the polarization direction of the incident light because of the monoclinic symmetry. Reflectance spectra simulated using parameters obtained from first-principle calculations are in good agreement with the experimental spectra. By adjusting the calculated phonon parameters so as to reproduce the experimental spectra, the polar phonon parameters were determined for six modes above 400 cm−1.