Electrochemically Fabricated SrGa 2 S 4 :Eu/ZnO-Vertical Nanowire Bilayer Scintillator for X-ray Imaging

Scintillators, which convert high-energy rays such as X-rays and positrons into visible and ultraviolet light, are incorporated as radiation detectors in X-ray computer tomography (X-ray CT) and positron emission tomography (PET), which system performances highly depends on the characteristics of the scintillator used. In this study, SrGa 2 S 4 :Eu/ZnO vertical nanowires (ZnO-vnws) bilayer scintillators were fabricated by electrodeposition of ZnO-vnws followed by electrophoresis deposition of SrGa 2 S 4 :Eu particles, and their structure, optical properties, and scintillator characteristics were evaluated. The ZnO-vnws were composed of vertically aligned ZnO nanowires with an excellent (001) out-of-plane orientation, and the SrGa 2 S 4 :Eu layer was composed of particles adhered to the ZnO-vnws. The SrGa 2 S 4 :Eu/ZnO-vnws bilayer scintillators emitted visible light at a wavelength of 533 nm with a lifetime of 0.389 μ s and functioned as a scintillator for X-ray irradiation. The resolution and luminescence intensity of the SrGa 2 S 4 :Eu/ZnO-vnws bilayer scintillators were improved by the introduction of the ZnO-vnws layer, when compared with those of the ZnO-vnws-free-SrGa 2 S 4 :Eu layer, when the thickness ratio of SrGa 2 S 4 :Eu layer to ZnO-nws length were 1.1 ∼1.3. The SrGa 2 S 4 :Eu/ZnO-vnws bilayer scintillator revealed a spatial resolution of 6.8 μ m, which was slightly larger than 5.4 μ m of a ready-made LuAG single-crystal scintillator.