In this paper, the effects of oxygen vacancy and gallium vacancy on the optical and scintillation properties of undoped β-Ga2O3 crystal and 2.5 mol % Al doped gallium oxide were investigated. For the undoped β-Ga2O3, the transmittance is improved after annealing in oxygen or nitrogen atmosphere. After the introduction of Al element, the absorption cutoff appears slightly blue shift, and the band gap increases. For the undoped as-grown β-Ga2O3 single crystals, the decay time consists of a fast component (τ1) of the order of nanoseconds, and two slow components (τ2, τ3) of tens to hundreds of nanoseconds. The contribution of the fast decay time component in the decay times is 2.78%. While for Al-doped β-Ga2O3, the faster (τ1) time is 2.33 ns for the as-grown one, and the contribution is 68.02%. However, the pulse height spectrum shows that the introduction of 2.5 mol % Al will reduce the light yield of the β-Ga2O3 crystal.

Sb-doped β-Ga 2 O 3 crystals were grown using the optical floating zone (OFZ) method. X-ray diffraction data and X-ray rocking curves were obtained, and the results revealed that the Sb-doped single crystals were of high quality. Raman spectra revealed that Sb substituted Ga mainly in the octahedral lattice. The carrier concentration of the Sb-doped single crystals increased from 9.55 × 10 16 to 8.10 × 10 18 cm −3 , the electronic mobility depicted a decreasing trend from 153.1 to 108.7 cm 2 • V −1 • s −1 , and the electrical resistivity varied from 0.603 to 0.017 Ω • cm with the increasing Sb doping concentration. The un-doped and Sb-doped β-Ga 2 O 3 crystals exhibited good light transmittance in the visible region; however, the evident decrease in the infrared region was caused by increase in the carrier concentration. The Sb-doped β-Ga 2 O 3 single crystals had high transmittance in the UV region as well, and the cutoff edge appeared at 258 nm.

Four single crystals (Yb 0.15 Lu 0.85x Y 0.85-0.85x ) 3 Al 5 O 12 (x = 0, 0.25, 0.5, 1) were grown by the Czochralski method. The correlation of the host atom Lu:Y ratios with the density and the luminescence properties were revealed. The density increases linearly with increasing of Lu 3 content, which will improve the gamma ray cut-off ability. The integrated intensity of the X-ray excited luminescence spectrum increases exponentially with the increasing Y:Lu ratio, while the decay time becomes even shorter with the increasing Lu 3 content. These results will provide a basis to balance the comprehensive properties to match different application requirements.