Mapping radiation-induced defects in CCDs through space and time
Mapping radiation-induced defects in CCDs through space and time
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通过空间和时间绘制 CCD 中辐射引起的缺陷图
DOI：
10.1117/12.2230142
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
A. Holland
中科院分区：
文献类型：
--
作者：
D. Hall;N. Bush;D. Wood;N. Murray;J. Gow;J. Skottfelt;A. Holland
电荷耦合器件（CCD）一直是许多天基应用的首选探测器。CCD将信号x射线或可见光转换成电子（n沟道器件）或空穴（p沟道器件），这些电子或空穴在集成期间存储在像素结构中，直到随后通过器件传输电荷包被读出。然而，这种信号电荷的转移并不是一个完美的过程。在太空任务的整个生命周期中，探测器将受到高能粒子和伽马射线的轰击。随着时间的推移，辐射会损坏探测器，导致电荷转移效率（CTE）下降，这是由于在探测器的硅晶格中产生缺陷或“陷阱”。这些缺陷在探测器硅的价带和导带之间产生额外的能级。电子或空穴（分别为n沟道或p沟道器件）通过缺陷位置可能被捕获。捕获的电子或空穴稍后将从陷阱中发射出来，受制于与相关缺陷的能级相关的发射时间常数。从信号中捕获和发射电荷会导致图像的特征拖尾或“模糊”，必须对其进行校正，以实现任务的科学目标。在过去的几年里，口袋抽油（或者严格地说“陷阱抽油”）技术的发展取得了很大的进步。该技术不仅可以将器件内的单个缺陷（或陷阱）定位到亚像素水平，而且还可以将诸如发射时间常数等陷阱参数的研究提高到新的精度水平。最近的出版物已经显示了这种技术在描述n和p通道器件中各种不同缺陷方面的力量，以及在校正技术中使用的潜力，然而，我们现在不仅在探索陷阱的位置和性质，而且在辐照后的时间内探索这些陷阱的生命周期。在轨道上，大多数设备将在低温下运行以抑制暗电流，因此设备在遭受辐射环境损害时是低温的。缺陷的迁移率随温度的变化而变化，因此低温辐照后出现的缺陷混合可能与室温辐照后或退火后发现的缺陷混合有很大差异。因此，在类轨道条件和较长时间尺度上研究圈闭的形成和运移是必要的。在本文中，我们介绍了n通道和p通道器件的陷阱泵浦的最新方法和结果，并展示了这种技术现在如何允许我们通过空间和时间来绘制ccd中辐射诱导的缺陷。
The Charge Coupled Device (CCD) has long been the detector of choice for many space-based applications. The CCD converts the signal X-rays or visible light into electrons (n-channel devices) or holes (p-channel devices) which are stored in the pixel structure during integration until the subsequent transfer of the charge packets through the device to be read out. The transfer of this signal charge is, however, not a perfect process. Throughout the lifetime of a space-based mission the detector will be bombarded by high-energy particles and gamma rays. As time progresses, the radiation will damage the detectors, causing the Charge Transfer Efficiency (CTE) to decrease due to the creation of defects or “traps” in the silicon lattice of the detector. The defects create additional energy levels between the valence and conduction band in the silicon of the detector. Electrons or holes (for n-channel or p-channel devices respectively) that pass over the defect sites may be trapped. The trapped electrons or holes will later be emitted from the traps, subject to an emission-time constant related to the energy level of the associated defect. The capture and emission of charge from the signal leads to a characteristic trailing or “smearing” of images that must be corrected to enable the science goals of a mission to be met. Over the past few years, great strides have been taken in the development of the pocket-pumping (or strictly-speaking “trap pumping”) technique. This technique not only allows individual defects (or traps) within the device to be located to the sub-pixel level, but it enables the investigation of the trap parameters such as the emission time constant to new levels of accuracy. Recent publications have shown the power of this technique in characterising a variety of different defects in both n- and p-channel devices and the potential for use in correction techniques, however, we are now exploring not only the trap locations and properties but the life cycle of these traps through time after irradiation. In orbit, most devices will be operating cold to suppress dark current and the devices are therefore cold whilst undergoing damage from the radiation environment. The mobility of defects varies as a function of temperature such that the mix of defects present following a cryogenic irradiation may vary significantly from that found following a room temperature irradiation or after annealing. It is therefore essential to study the trap formation and migration in orbit-like conditions and over longer timescales. In this paper we present a selection of the latest methods and results in the trap pumping of n- and p-channel devices and demonstrate how this technique now allows us to map radiation-induced defects in CCDs through both space and time.
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DOI：
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期刊：
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DOI：
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期刊：
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