Electroreflectance study on optical anisotropy in β-Ca_2O_3

摘要

Electroreflectance (ER) spectra of beta-Ga2O3 were measured using Schottky barrier diodes. The ER spectra were well fitted to a third derivative line shape function by assuming three excitonic transitions. The transition energies exhibited moderate blueshifts with an external reverse bias by reflecting the contribution of transitions at M-0 type critical points. Optical anisotropy was selectively observed in the polarized ER spectra. The fittings for the third derivative line shape function gave relatively large broadening parameters (0.11-0.89 eV) due mainly to the large exciton-longitudinal-optical-phonon interaction in beta-Ga2O3. The ER spectra exhibited a third derivative line shape with a Franz-Keldysh oscillation superimposed on it. The results demonstrate that ER measurements are useful for investigating optical anisotropy in beta-Ga2O3 and related alloys. Published under license by AIP Publishing.