We characterize a hybrid pixel direct detector and demonstrate its suitability for electron energy loss spectroscopy (EELS). The detector has a large dynamic range, narrow point spread function, detective quantum efficiency ≥ 0.8 even without single electron arrival discrimination, and it is resilient to radiation damage. It is capable of detecting ~5 × 106 electrons/pixel/second, allowing it to accommodate up to 0.8 pA per pixel and hence >100 pA EELS zero-loss peak (ZLP) without saturation, if the ZLP is spread over >125 pixels (in the non-dispersion direction). At the same time, it can reliably detect isolated single electrons in the high loss region of the spectrum. The detector uses a selectable threshold to exclude low energy events, and this results in essentially zero dark current and readout noise. Its maximum frame readout rate at 16-bit digitization is 2250 full frames per second, allowing for fast spectrum imaging. We show applications including EELS of boron nitride in which an unsaturated zero loss peak is recorded at the same time as inner shell loss edges, elemental mapping of an STO/BTO/LMSO multilayer, and efficient parallel acquisition of angle-resolved EEL spectra (S(q, ω)) of boron nitride.

中文翻译：

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用于电子能量损失光谱的混合像素直接检测器

我们表征了混合像素直接检测器，并证明其适用于电子能量损失光谱 (EELS)。该探测器动态范围大，点扩散函数窄，探测量子效率≥0.8，即使没有单电子到达鉴别，也具有抗辐射损伤的能力。它能够检测约 5 × 106 电子/像素/秒，使其每像素最多可容纳 0.8 pA，因此，如果 ZLP 分布在 >125 个像素上，则可容纳 >100 pA 的 EELS 零损耗峰值 (ZLP) 而不饱和（在非分散方向）。同时，它可以在光谱的高损耗区域可靠地检测孤立的单电子。检测器使用可选阈值来排除低能量事件，这导致暗电流和读出噪声基本上为零。其 16 位数字化时的最大帧读出率为每秒 2250 全帧，可实现快速光谱成像。我们展示的应用包括氮化硼的 EELS，其中不饱和零损耗峰值与内壳损耗边缘同时记录，STO/BTO/LMSO 多层的元素映射，以及角分辨 EEL 光谱（S (q, ω)) 的氮化硼。