The effect of different oxidative growth conditions on the scintillation properties of Ce: Gd₃Al₃Ga₂O₁₂ crystal

Ce-doped Gd₃Al₃Ga₂O₁₂ (Ce:GAGG) crystal shows good scintillation performances, especially high light yield. However, its scintillation decay contains slower components. Such phenomenon is due to the delayed radiative recombination process which is caused by trapping effects in the transport stage of scintillation mechanism. Various defects including oxygen vacancy can give rise to shallow traps in the forbidden gap of the material which can cause such phenomena. To study the influence of such oxygen defects, 0.2-mol% Ce-doped GAGG single crystals were grown by Floating Zone method using growth atmosphere with different oxygen concentrations. The optical and scintillation properties of the crystals were examined. The light yield and emission wavelength of these samples did not depend on the oxygen content in the growth atmosphere. On the other hand, scintillation decays of the samples grown under the high oxygen concentrations (100 and 40% oxygen) were faster than that of the sample grown under the lower concentration (20%). Oxygen content in the growth atmosphere thus appears an important parameter in the optimization of the growth process of these materials.