High signal-to-noise ratio HgI_2 X-ray detector assisted with ultraviolet radiation

摘要

A direct-conversion active matrix flat panel X-ray imaging detector was fabricated with an HgI2 photoconductor. The HgI2 photoconductive layer was coated on an amorphous Si thin film transistor panel with a particle-in-binder process. The micro-morphological properties of the HgI2 photoconductive layer were characterized by micro-computed tomography, X-ray diffraction, and scanning electron microscopy. The volume density of HgI2 in the layer was 40.9%. The effect of the bias voltage on the sensitivity of the HgI2 photoconductor was investigated with different photon irradiations such as ultraviolet and visible light as one of reset processes. The sensitivity of the HgI2 photoconductor was increased with the help of ultraviolet radiation before X-ray radiation, which released trapped carriers inside the photoconductor and increased the sensitivity of the HgI2 photoconductor. Moreover, ultraviolet irradiation with a DC bias stabilized the sensitivity variation. An X-ray imaging detector in conjunction with anHgI(2) photoconductor shows a very high signal-to-noise ratio.