Significant enhancement in light output of photonic-crystal-based YAG:Ce scintillator for soft X-ray detectors

Because of its high light output, Gd2O2 S:Tb (P43) phosphor powder is widely used in scintillator detectors for scanning transmission soft X-ray microscopy. However, the long decay time (>1 ms) of P43 phosphor powder limits the image scanning speed. Inorganic scintillators such as YAG:Ce are very suitable for fast scanning imaging due to their short decay time (tens of nanoseconds). Nevertheless, its light output is lower than that of P43 phosphor powder. Patterning photonic crystals (PhCs) on the output surface of an inorganic scintillator is a simple and efficient method to enhance its light output. In this article, we use a soft X-ray interference lithography technique to produce a large-area pattern of nanoscale PhCs on a 200- $\mu \text{m}$ -thickness and 1-in-diameter YAG:Ce scintillator. Measurement of the enhancement ratio was performed on the soft X-ray beamline (BL08U1A) at the Shanghai Synchrotron Radiation Facility. The results show that the light output of the PhC-patterned YAG:Ce scintillator with air coupling is approximately 2.8 times higher than that of the unpatterned YAG:Ce scintillator. Meanwhile, the time-resolved emission with optical excitation showed that the PhC structures did not affect the spontaneous emission rate in the internal of scintillator crystal. This enhancement of the light output indicates that the PhC-patterned YAG:Ce scintillator is a good candidate for soft X-ray detection.