Experimental and theoretical study of defect-driven scintillation from γ−Ga2O3 nanophosphor-embedded transparent glass-ceramics

Gallium oxide (${\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$), as a representative of the four-generation ultrawide band-gap semiconductors, emerges to be a promising candidate for high performance scintillators. However, the full exploitation of its scintillation properties and the understanding of the defect-driven luminescence mechanisms are still lacking especially for $\ensuremath{\gamma}\ensuremath{-}\mathrm{G}{\mathrm{a}}_{2}{\mathrm{O}}_{3}$ nanocrystals (NCs) grown in glass. Here, the easy-to-process glass-making and post-thermal treatment method is used to prepare $\ensuremath{\gamma}\ensuremath{-}\mathrm{G}{\mathrm{a}}_{2}{\mathrm{O}}_{3}$ NC embedded transparent glass-ceramics (GCs). X-ray excited bright visible blue-green emissions are observed from the $\ensuremath{\gamma}\ensuremath{-}\mathrm{G}{\mathrm{a}}_{2}{\mathrm{O}}_{3}$ NC embedded GCs, which are attributed to the donor-acceptor pair (DAP) recombination. Positive luminescence hysteresis is found to occur in the processes of both ultraviolet (UV) light excited photoluminescence and the x-ray excited luminescence (XEL). A method of prolonged UV preirradiation is used to counteract the hysteresis effect, which is desirable from the application point of view. Monte Carlo simulation is employed to reveal the difference between x- and $\ensuremath{\gamma}\ensuremath{-}\mathrm{ray}$ photoresponse of the GCs, and the results are compared with those of the ${\mathrm{Bi}}_{4}{\mathrm{Ge}}_{3}{\mathrm{O}}_{12}$ crystal. First-principles calculations are carried out to investigate the intrinsic defect properties of $\ensuremath{\gamma}\ensuremath{-}\mathrm{G}{\mathrm{a}}_{2}{\mathrm{O}}_{3}$. Our results provide a theoretical foundation to understand the relevant defects responsible for the observed DAP, and offer potential avenues for tailoring optical performance for various applications. As a proof-of-concept, an x-ray imaging system is built on the studied GC scintillator, exhibiting performance superior to that of the eye-catching ${\mathrm{CsPbBr}}_{3}$ perovskite NC embedded GCs.