Spectroscopic ellipsometry studies on β-Ga2O3 films and single crystal

Anisotropic optical properties are investigated on beta-Ga2O3 films and a single crystal by spectroscopic ellipsometry measurements. The (2011) films grown on (0001) alpha-Al2O3 contain threefold in-plane rotational domains, and the refractive index and absorption coefficient a obtained by assuming an isotropic material are found to be smaller than those in the single crystal. By measuring the off-normal transmission ellipsometry spectra of the (010) beta-Ga2O3 substrate, the optical anisotropy in a biaxial crystal as well as the gradual increase in a are recognized as origins of the scattering in optically determined bandgap energies. (C) 2016 The Japan Society of Applied Physics