산화물을 첨가한 HgI2 엑스선 검출기의 특성 평가

A Performance Analysis of HgI2 X-ray Detector Mixed Oxidation Materials

To improve the performance of HgI2 composite x-ray detector, we studied its structure that reduced charge trap and estimated electrical properties as incident x-ray energy. The composite detector exhibits lower performance in x-ray sensitivity, dark current, and reproducibility than single-crystal detector or poly-crystal detector, because dielectric constant of polymeric glue and grain size of semiconductor particles affected charge transport properties. Therefore, in order to improve the charge transport properties, metal oxide such as SiO2 or TiO2 were added to HgI2 composite x-ray detector and its characteristics were investigated. The effect of metal oxide in HgI2 composite was analysed by comparing the properties of metal oxide mixed HgI2 composite x-ray detector with those of simple HgI2 composite x-ray detector. The samples were divided into three kinds of films, HgI2/TiO2 composite x-ray detector, HgI2/SiO2 composite x-ray detector, and simple HgI2 composite x-ray detector. All samples were fabricated by sedimentation method, one kind of particle-in-binder (PIB) methods. And the each thickness of them was around 200um. To investigate electrical properties of the samples, dark current of samples was measured as a function of applied bias. As a result, when 1 V/um of the electric field was applied, 4.78 nA/cm2, 16.58 nA/cm2, and 7.10 nA/cm2 were measured for HgI2/SiO2 composite x-ray detector, HgI2/TiO2 composite x-ray detector, and simple HgI2 composite x-ray detector. And then x-ray sensitivity of samples was measured in RQA-5 condition (70kVp, 100mA, 0.03s, 21mmAl phantom). The result respectively showed 23.15 nC/mR/cm2, 19.25 nC/mR/cm2, and 24.25 nC/mR/cm2 of x-ray sensitivity for the each samples. Furthermore, reproducibility, aging effect, and signal lag of samples were measured. Consequentially, the all measured results like dark current, x-ray sensitivity, reproducibility, and signal lag showed the best properties in HgI2/SiO2 composite x-ray detector among three kinds of samples