γ-CuI超快闪烁转换屏的制备与性能表征  

Preparation and Performance of Ultrafastγ-CuI Scintillation Conversion Screen

作　　者：夏明[1] 顾牡[1] 刘小林[1] 刘波[1] 黄世明[1] 倪晨[1] 

机构地区：[1]同济大学物理科学与工程学院,上海市特殊人工微结构材料与技术重点实验室,上海200092

出　　处：《光谱学与光谱分析》2015年第4期1079-1083,共5页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(11475128,11375129,11475127);科学技术部国家重大科学仪器设备开发专项项目(2011YQ3001902)资助

摘　　要：以石英基片为衬底,采用真空热蒸发法,通过调控衬底温度制备出了具有微柱结构、柱径在μm量级、厚度约17μm的γ-CuI超快闪烁转换屏。在X射线激发下,所制备的γ-CuI超快转换屏具有峰位在430nm的快成分发射峰和峰位在700nm的慢成分发射带,其中快成分发射峰占总发光的主要部分;随着衬底温度由170℃升高至210℃,转换屏430nm发射峰的强度会逐渐减弱,而700nm发射带的强度则逐渐增强,这可能是由于较高的衬底温度会造成碘流失从而引起转换屏中碘空位增加、铜空位减少所致(Cu/I增大),碘流失的假设得到了卢瑟福背散射实验的验证。γ-CuI超快转换屏的晶体结构呈(111)晶面择优取向,且不随衬底温度而变化,当衬底温度升高至210℃时,由于CuI分子获得的动能增加,转换屏还会出现微弱的(220)和(420)晶面的取向。当衬底温度由170℃增至190℃时,转换屏的微柱结构会随之优化,微柱结构明显,但当衬底温度进一步增至210℃时,由于表面扩散和体扩散效应加剧,微柱结构会随之退化。最后,采用刃边法测量了所制备γ-CuI转换屏的空间分辨率,结果显示170,190和210℃衬底温度条件下所制备的转换屏,其空间分辨率分别为:4.5,7.2和5.6lp·mm-1,微柱结构有助于提高转换屏的空间分辨率。Micro‐columnar structured γ‐CuI scintillation conversion screen with columnar diameter in the micrometer and thick‐ness about 17 μm were prepared by thermal evaporation method on quartz substrates with different temperatures .X‐ray excited luminescence spectra of the screens show two peaks located at 430 nm and near 700 nm ,which correspond to the fast and slow emission components ,respectively .The fast one dominated .The intensity of 430 nm peak decreased as the substrate tempera‐ture rose from 170 ℃ to 210 ℃ .At the same time the intensity of 700 nm band increased .The changes may be attributed to the iodine loss from screen caused by the substrate temperature .The phenomenon of iodine loss was observed by the Rutherford backscattering experiment .The crystal structure of the screens presents （111） preferred orientation ,which is independent of the substrate temperature .As the temperature rose to 210 ℃ ,two weak additional peaks of （220） and （420）γ‐CuI crystal planes in X‐ray diffraction patterns appeared due to the increase in kinetic energy of CuI molecules .The scanning electron microscopy ima‐ges of the screens showed that the columnar structure was improved when the substrate temperature increased from 170 ℃ to 190 ℃ ,but it would be degenerated when the temperature continued to rise to 210 ℃ because of the surface and bulk diffusion effects of the depositing molecules .Finally ,the spatial resolution of the γ‐CuI scintillation screens was measured by knife‐edge method ,and they are 4.5 ,7.2 and 5.6 lp · mm^-1 for the screens prepared at the substrates temperatures of 170 ,190 and 210℃ ,respectively .The result shows that micro‐column structure could improve the spatial resolution of γ‐CuI scintillation screen .

关 键 词：γ-CuI超快闪烁转换屏 真空热蒸发法 微柱结构 X射线激发发射光谱 空间分辨率 

分 类 号：O482.3[理学—固体物理]