光学
场发射枪
次级电子
场电子发射
电子枪
分辨率(逻辑)
亮度
扫描电子显微镜
扫描透射电子显微镜
显微镜
电子
镜头(地质)
材料科学
探测器
信号(编程语言)
物理
阴极射线
人工智能
程序设计语言
量子力学
计算机科学
出处
期刊:Proceedings ... annual meeting, Electron Microscopy Society of America
[Cambridge University Press]
日期:1988-01-01
卷期号:46: 182-183
被引量:4
标识
DOI:10.1017/s0424820100102997
摘要
In recent years great improvements in the resolution of secondary electron imaging have been made possible by (1) using a high brightness field emission gun and (2) putting the specimen inside the highly excited objective lens pole-pieces in a scanning electron microscope. Hence, a resolution of 0.8 nm of SE images obtained with a 30 kv electron microscope has been claimed and atom-high surface steps have been observed by detecting SE signals. In a STEM instrument the SE signals are collected at the exit surface of the sample. The emitted secondary electrons spiral up around the fringe magnetic field lines of the objective lens before they are collected by the SE detector. Only type I secondary electrons contribute to the image formation signal in this detecting configuration. The collection efficiency may be high due to the effect of the pre-collection magnetic field and the signal-to-noise ratio is good with the use of a field emission gun.
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