Hybrid Pixel Detectors for Next-Generation Diffraction Cameras in Scanning Electron Microscopy

电子背散射衍射(EBSD)是一种扫描电子显微镜(SEM)技术，可以从纳米、微观到宏观层面分析晶体材料的性质。它使用一台灵敏的相机来记录在样品上一系列纳米级斑点上产生的电子背向散射衍射图案(EBSP)，因为它被聚焦的电子束“映射”。EBSD是许多领域研究和开发的重要工具，包括：冶金、半导体和地质。在许多EBSD实验中，分析的灵敏度和速度受到现有相机的限制，显然需要改进。相机灵敏度的提高将允许捕获高质量的EBSP，同时对样品施加较低的电子剂量。开发更高灵敏度的EBSD相机将允许更快的操作速度，从而增强EBSD在所有应用中的吸引力。它将开辟学术和工业感兴趣的新领域，包括到目前为止还不适用于EBSD的光束敏感材料。目前的EBSD相机使用间接电子检测(IED)，其灵敏度受到光子(由荧光屏上的电子产生)通过光学与图像传感器的低效耦合的限制。相反，图像传感器上的直接电子检测(DED)可以提高灵敏度(即去除低效光学元件)，并且可以通过使用混合像素探测器(HPD)来实现，该混合像素探测器包括绑定到电子计数专用集成电路(ASIC)的半导体传感器，例如Medipix系列中的传感器。该项目寻求在我们早期工作的基础上，开发基于最新一代Medipx4 ASIC的HPD，该ASIC针对EBSD进行了优化，并具有显著增强的灵敏度。“

"Electron Backscatter Diffraction (EBSD) is a Scanning Electron Microscopy (SEM) technique to analyse the properties of crystalline materials at scales from the nano- and micro-, up to the macroscopic level. It uses a sensitive camera to record the Electron Backscatter Diffraction Pattern (EBSP) generated at each of a series of nano-scale spots on a specimen as it is ""mapped"" by the focussed electron beam.EBSD is an important tool for research and development in many fields, including: metallurgy; semiconductors; and geology. In many EBSD experiments the sensitivity and speed of analysis is limited by the cameras currently available, and there is a demonstrated need for improvement. Increased sensitivity of the camera would allow for the capture of high-quality EBSPs with lower electron doses applied to the specimen. Development of a higher-sensitivity EBSD camera will allow for higher-speed operation and hence enhance the appeal of EBSD across all applications. It will open new areas of both academic and industrial interest, including for beam-sensitive materials that have not so far been amenable to EBSD.Current EBSD cameras use Indirect electron Detection (IeD) with sensitivity limited by inefficient coupling of photons (generated by electrons at a phosphor screen) via optics to the image sensor. Instead, Direct electron Detection (DeD) at the image sensor (i.e. removing the inefficient optics) can enhance sensitivity and may be realised by the use of a Hybrid Pixel Detector (HPD) comprising a semiconducting sensor bonded to an electron-counting Application Specific Integrated Circuit (ASIC) such as those in the Medipix family. The project seeks to build on our early work and develop an HPD based on latest-generation Medipx4 ASIC, optimised for EBSD and with substantially enhanced sensitivity."