arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1509.00538physics.ins-det
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提高京都SOI像素传感器的电荷收集效率

Improving Charge-Collection Efficiency of Kyoto's SOI Pixel Sensors

Hideaki Matsumura, Takeshi Go Tsuru, Takaaki Tanaka, Ayaki Takeda, Makoto Ito, Syunichi Ohmura, Yasuo Arai, Koji Mori, Yusuke Nishioka, Ryota Takenaka, Takayoshi Kohmura

摘要:

我们一直在为X射线天文学的下一代卫星开发X射线SOIPIX。它们的高时间分辨率($\sim10~μ$ s)和事件触发输出功能使我们能够在无堆积的情况下进行读取并使用反符合系统。它们在成像光谱学中的性能与CCD相当。在我们以前的模型中的一个问题是在像素边界的电荷收集效率(CCE)的退化。我们使用SPring-8处的$10~μ$ m Φ $的精细准直X射线束测量了亚像素尺度的响应,并研究了像素内CCE的非均匀性。我们发现,X射线检测效率和CCE降低在像素电路下的传感器区域放置在掩埋的p阱(BPW)外。电场的2D模拟表明,BPW外部的隔离像素电路在传感器和掩埋氧化物层之间的界面处的电势中产生局部最小值。因此,信号电荷的一部分被捕获在那里,并且不被收集到BPW。基于这一结果,我们修改了像素内电路的布置,使得电场将朝向BPW会聚。我们证实,在像素边界的CCE是成功地改善了更新后的模型。

英文摘要:

We have been developing X-ray SOIPIXs for next-generation satellites for X-ray astronomy. Their high time resolution ($\sim10~μ$s) and event-trigger-output function enable us to read out without pile-ups and to use anti-coincidence systems. Their performance in imaging spectroscopy is comparable to that in the CCDs. A problem in our previous model was degradation of charge-collection efficiency (CCE) at pixel borders. We measured the response in the sub-pixel scale, using finely collimated X-ray beams at $10~μ$mΦ$ at SPring-8, and investigated the non-uniformity of the CCE within a pixel. We found that the X-ray detection efficiency and CCE degrade in the sensor region under the pixel circuitry placed outside the buried p-wells (BPW). A 2D simulation of the electric fields shows that the isolated pixel-circuitry outside the BPW creates local minimums in the electric potentials at the interface between the sensor and buried oxide layers. Thus, a part of signal charge is trapped there and is not collected to the BPW. Based on this result, we modified the placement of the in-pixel circuitry so that the electric fields would converge toward the BPW. We confirmed that the CCE at pixel borders is successfully improved with the updated model.

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