Application of the Mesh Experiment for the Back-Illuminated Charge-Coupled Device: I. Experiment and the Charge Cloud Shape
Application of the Mesh Experiment for the Back-Illuminated Charge-Coupled Device: I. Experiment and the Charge Cloud Shape
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背照式电荷耦合器件网格实验的应用：一、实验与电荷云形状
DOI：
10.1143/jjap.41.5827
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发表时间：
2002
影响因子：
1.5
通讯作者：
Kouei Yamamoto
中科院分区：
文献类型：
--
作者：
E. Miyata;Masami Miki;J. Hiraga;Hirohiko Kouno;Kazutoshi Yasui;H. Tsunemi;K. Miyaguchi;Kouei Yamamoto
我们对背照式 (BI) 电荷耦合器件 (CCD) 采用了网格实验。 BI CCD 具有与前照式 (FI) CCD 相同的结构。由于 X 射线光子从 CCD 的背面进入，因此在远离电极的地方形成初级电荷云。初级电荷云通过扩散过程扩展，直到到达电极下方的势阱。因此，产生的电荷云的扩散时间比 FI CCD 中的扩散时间长，从而产生比预期更大的电荷云尺寸。网格实验使我们能够指定与亚像素分辨率相互作用的 X 射线点。我们测量了 BI CCD 中产生的电荷云形状。我们发现电荷云形状有两个不同大小的部分：窄部分和宽部分。窄元件的尺寸为 2.8–5.7 µm（以标准差为单位），很大程度上取决于入射 X 射线在 Si 中的衰减长度。 X射线的衰减长度越短，电荷云越大。该结果在质量上与 CCD 内部的扩散模型一致。另一方面，宽成分的尺寸大致恒定在 ≃13 µm，并且不依赖于 X 射线能量。从CCD的设计值和各元件的比例来看，窄元件起源于耗尽区，而宽元件起源于无场区。
We have employed a mesh experiment for back-illuminated (BI) charge-coupled devices (CCDs). BI CCDs possess the same structure as front-illuminated (FI) CCDs. Since X-ray photons enter from the back surface of the CCD, a primary charge cloud is formed far from the electrodes. The primary charge cloud expands through a diffusion process until it reaches the potential well that is just below the electrodes. Therefore, the diffusion time for the charge cloud produced is longer than that in the FI CCD, yielding a larger charge cloud size than expected. The mesh experiment enables us to specify the X-ray point of interaction with subpixel resolution. We measured a charge cloud shape produced in the BI CCD. We found that there are two components of the charge cloud shape having different sizes: a narrow component and a broad component. The size of the narrow component is 2.8–5.7 µm in units of standard deviation and strongly depends on the attenuation length of incident X-rays in Si. The shorter the attenuation length of the X-rays, the larger the charge cloud. This result is qualitatively consistent with a diffusion model inside the CCD. On the other hand, the size of the broad component is roughly constant at ≃13 µm and does not depend on X-ray energies. Judging from the design value of the CCD and the fraction of each component, we conclude that the narrow component has its origin in the depletion region whereas the broad component originates in the field-free region.