摘要
中子深度剖面分析(Neutron Depth Profiling,NDP)是一种高灵敏、高分辨测量材料近表面深度分布信息的无损检测技术,利用中国先进研究堆(China Advanced Research Reactor,CARR)冷中子束建立了一套中子深度剖面分析系统,该系统真空度优于其他NDP设备,可达到3.4×10-5 Pa。冷中子注量率高是其另一大优势,CARR在15 MW功率下运行时,用金活化法测得中子导管末端的中子注量率约为4.8×108cm-2?s-1。此外,该系统一次性可以测量6个样品,简单易行。通过测试美国国家标准与技术研究院(National Institute of Standards and Technology,NIST)标准物质SRM-2137评价CARR-NDP系统的性能,测量结果与参考值具有较好的一致性,验证了CARR-NDP系统的可行性。
[Background] Neutron depth profiling(NDP) is a non-destructive near-surface analysis technique and it is widely used in characterization of polymers, semiconductors, alloys, lithium ion battery materials, photoelectric materials and many other materials. [Purpose] This study aims is to develop NDP system to obtain the depth profiles of several crucial light nuclides(e.g.,6 Li and10 B) in nearly any substrate. [Methods] Based on the cold neutron beam of China advanced research reactor(CARR), a NDP system was developed with vacuum reached 3.4 × 10-5 Pa and neutron flux rate of 4.8 × 108 cm-2?s-1. The standard reference material(SRM-2137) sample was used to test the performance of this NDP system. The measured α-particle spectrum was calculated by the inversion iterative algorithm to obtain the depth profiles of crucial elements. [Results] The experimental results show that the simulation results of SRM-2137 agree well with the experimental results. The maximum error is less than 4% at each layer of5 nm thickness. The peak depth is very close to the reference value(188 nm). The depth accuracy is 0.53%.[Conclusions] Established CARR-NDP system and relevant experiments and data analysis techniques have been verified. The system will be further applied to investigating the lithium ion batteries, multilayer films and hightemperature alloys, etc.
引文
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