Temperature-dependent cathodoluminescence spectra were measured from (001) unintentionally doped, (100) Si-doped, and (010) Mg-doped β-Ga2O3 substrates prepared by either the floating zone growth or edge-defined film-fed growth methods. Although β-Ga2O3 is expected to be an indirect bandgap material, direct Γ-Γ transitions were found to be dominant in the optical transmittance spectra. The substrates exhibited no near-band-edge emission and instead exhibited ultraviolet luminescence, blue luminescence (BL), and green luminescence bands. Since the BL intensity strongly depended on the resistivity in the crystals, there was evidence of a correlation between the BL intensity and formation energy of oxygen vacancies.

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D. (2021). Energetic α -particle sources produced through proton-boron reactions by high-energy high-intensity laser beams. Physical Review E, 103(5), [053202].

We report experimentally observed linear dichroism in angle-resolved core-level photoemission spectra of PrIr2Zn20 and PrB6 in cubic symmetry. The different anisotropic 4f charge distributions between the compounds due to the crystalline-electric-field splitting are responsible for the difference in the linear dichroism, which has been verified by spectral simulations with the full multiplet theory for a single-site Pr 3+ ion in cubic symmetry. The observed linear dichroism and polarization-dependent spectra in two different photoelectron directions for PrIr2Zn20 are reproduced by theoretical analysis for the Γ3 ground state, whereas those of the Pr 3d and 4d core levels indicate the Γ5 ground state for PrB6.