Improved epitaxy of CsI(Tl) film on Si substrate buffered by graphene for X-ray detection
Improved epitaxy of CsI(Tl) film on Si substrate buffered by graphene for X-ray detection
复制标题
DOI：
10.1016/j.ceramint.2023.05.043
复制
发表时间：
2023-05
影响因子：
5.2
通讯作者：
Chunhui Tian;Shuang Liu;Yi-Fu Xie;Lina Guo;Shenglan Wu;Xixi Liu;Dejun Chen;Shang-jian Zhang;Y. Liu;Z. Zhong
中科院分区：
文献类型：
--
作者：
Chunhui Tian;Shuang Liu;Yi-Fu Xie;Lina Guo;Shenglan Wu;Xixi Liu;Dejun Chen;Shang-jian Zhang;Y. Liu;Z. Zhong
沉积在玻璃衬底上的具有与主流半导体电路相匹配的适当波长的CsI（Tl）闪烁体的生长对于X射线成像行业至关重要。但是，光放大器和硅基光传感器之间的耦合损耗限制了其性能。因此，在单晶硅上制备CsI（Tl）薄膜对下一代高性能X射线成像器件具有重要意义。然而，CsI（Tl）和Si之间的晶格失配和热失配会导致CsI（Tl）闪烁转换器的形貌和结构恶化，从而降低CsI（Tl）闪烁转换器的性能。本文报道了利用石墨烯（Gr）作为缓冲层，在Si（111）衬底上进行CsI（Tl）薄膜的货车德瓦尔斯外延生长，并展示了其应用前景。引入的石墨烯缓冲层极大地释放了CsI（Tl）和Si衬底之间的应力。因此，CsI（Tl）薄膜具有良好的微柱状结构和晶体结构，与裸Si（111）衬底相比，CsI（Tl）薄膜具有更高的光输出和信噪比，更好的调制传递函数和条形X射线图像。这种简便的方法不仅为在硅基探测器上外延CsI（Tl）等碱金属卤化物晶体及其在辐射探测中的应用奠定了基础，而且为在柔性衬底上沉积CsI（Tl）晶体开辟了新的前景。
The growth of the CsI(Tl) scintillators deposited on glass substrates with proper wavelength matching the mainstream semiconductor circuits is crucial for X-ray imaging industry. But the coupling loss between the scintillators and silicon based photo sensors has limited the performance. So fabricating CsI(Tl) films on monocrystalline silicon is greatly important for next-generation high performance X-ray image devices. However, the lattice and thermal mismatch between CsI(Tl) and Si always deteriorates the morphology and structure, and thus degrades the property of the CsI(Tl) scintillation converters. Here, by utilizing crystalline graphene(Gr) as a buffer layer, the van der Waals epitaxial growth of CsI(Tl) film on Si(111) substrate is reported and its advanced applications are demonstrated. The introduced graphene buffer layer extremely frees the stress between CsI(Tl) and Si substrate. Therefore, the CsI(Tl) films show perfect micro-columnar and crystalline structures, and then, exhibit much higher light output and signal to noise ratio, and better modulation transfer functions and a bar pattern X-ray image compared to that on bare Si(111) substrate. This facile method not only lays the foundation for the epitaxy of the alkali halide crystals, including CsI(Tl), onto Si-based detectors and its applications in radiation detection, but also may broaden a new perspective of deposition of CsI(Tl) scintillators into flexible substrates.