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中国物理学会期刊

基于ZnO:In纳米棒阵列的X射线闪烁转换屏制备与性能研究

CSTR: 32037.14.aps.69.20200282

Preparation and properties for X-ray scintillation screen based on ZnO:In nanorod arrays

CSTR: 32037.14.aps.69.20200282
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  • 为了满足高能物理和核物理领域在探究一些超快物理事件时, 对兼顾高时间和高空间分辨的X射线闪烁转换屏的迫切需求, 本文利用磁控溅射和水热反应法制备了ZnO:In纳米棒阵列X射线闪烁转换屏, 并对其进行氢气氛下的等离子处理优化其闪烁发光性能. X射线激发发射谱显示ZnO:In纳米棒阵列具有395 nm的紫外发光和450—750 nm的可见发光两个发光峰, 同时表明氢气氛等离子体处理可显著增强ZnO:In纳米棒阵列的紫外发光, 抑制其可见发光. 发光衰减时间测量表明, ZnO:In纳米棒阵列紫外发光衰减时间在亚纳秒级, 其可见发光衰减时间在纳秒级, 两者均可满足高时间分辨的X射线探测需求. 在上海同步辐射光源的X射线空间分辨率测试表明, 在能量为20 keV的X射线光束辐照下, 厚度为12 μm的ZnO:In纳米棒阵列作为X射线闪烁转换屏可达到1.5 μm的系统空间分辨率. 本研究表明利用ZnO:In纳米棒阵列作为X射线闪烁转换屏是实现兼顾高时间和高空间分辨的X射线探测与成像的一种可行方案.

     

    X-ray scintillation screens as the core component of X-ray imaging detectors have widespread applications in the medical imaging, security inspection, high energy physics, radiochemistry, and so on. For a long time, the development of X-ray scintillation screen mainly focuses on improving the light yield in order to enhance its detection efficiency. However, a novel tendency has recently emerged for ultrafast time performance of the X-ray imaging detector. The indium doping zinc oxide (ZnO:In) with high radiation hardness, higher light yield(>10000 photons/MeV) and subnanosecond decay time is a promising scintillation material for ultrafast detections. In order to satisfy the requirements of X-ray scintillation screens with ultrafast and high-spatial-resolution in the existing and upcoming high energy physics experiments, the ZnO:In nanorod arrays have been prepared on a 100-nm-thick ZnO-seeded substrate by hydrothermal reaction method and then treated by hydrogen plasma in present work. The results of SEM demonstrate the average diameter and length of the ZnO:In nanorods are about 0.5 and 12 μm, respectively. The XRD shows the ZnO:In nanorods are highly aligned perpendicular to the substrate along c-axis direction. The X-ray excited luminescence spectra show that two luminescence bands are observed, i.e. an ultraviolet emission peak located at about 395 nm and a visible emission band at 450–750 nm. It is particularly important to point out that hydrogen plasma treatment can enhance the ultraviolet emission of ZnO:In nanorod arrays and suppress its visible emission. The reason is attributed to the formation of shallow donors through hydrogen entering the ZnO and the combination of VO and Oi. In addition, the fluorescence decay times of the ultraviolet and visible emissions for the ZnO:In nanorod arrays are subnanosecond and nanosecond, respectively, satisfying the demand of the fast X-ray imaging. The spatial resolution of ZnO:In nanorod arrays has been characterized in X-ray imaging beamline at the Shanghai Synchrotron Radiation Facility. Under excitation of the X-ray beam with the energy of 20 keV, a system spatial resolution of 1.5 μm could be achieved by using an 12 μm thickness ZnO:In nanorod arrays as the scintillation screen, which is exceeded the highest level had ever been reported on ZnO:In nanorod arrays scintillation screen. In conclusion, this present work shows that it is a feasible solution for X-ray detection and imaging with high temporal and spatial resolution by using ZnO:In nanorod arrays as the X-ray scintillation screen.

     

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