Effect of Microstructure on Photo-Induced Current Characteristics of Eu2+-Doped SrAl2O4

Research interest is active in Eu2+/Dy(3-)doped SrAl2O4 phosphors, and the photocurrent characteristics of Eu2+-doped SrAl2O4 without Dy3+ was investigated extensively. However, it exhibits a low photocurrent of similar to 1 mu A owing to high resistance. In this study, the changes in a photo-induced current with grain size were examined. The effect of the processing methods on the microstructure and photocurrent characteristics of Eu2+-doped SrAl2O4 phosphors was investigated. (Sr0.99Eu0.01)Al2O4 powders were synthesized using a conventional solid-state method and calcined at 1350 degrees C under a 3% H-2/(Ar + H-2) reducing gas atmosphere. Sample pellets were fabricated as conventional and hot-press-sintered bodies at 1400 degrees C. A thin film of the sample was deposited on an alumina substrate by radio-frequency magnetron sputtering. Scanning electron microscopy revealed that the hot-press-sintered body has larger grains than the conventionally sintered body. The photo-induced current of the hot-press-sintered body at 400 lx was similar to 100 and similar to 1000 times higher than those of the conventionally sintered body and thin film, respectively. Impedance analysis confirmed that this dramatic increase in the photo-induced current is closely related to the increase in the grain size and crystallinity of the sample. This study verifies the applicability of Eu2+-doped SrAl2O4 as both a phosphor and photosensor.