EM Improvements for Reducing Beam Damage
- Practical Electron Microscopy and Database -
- An Online Book -

http://www.globalsino.com/EM/  



 
This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
 

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Reducing the accelerating voltage of the electron beams in EMs, e.g. STEM and TEM, helps to avoid beam damage in specimens but will degrade the spatial resolution and/or the contrast of the images. Fortunately, some efforts can be performed to compensate for these negative effects. For instance, a TEM/STEM system equipped with a cold field emission gun and spherical aberration correctors for image- and probe-forming systems can still have high spatial resolution to resolve the lattice fringes of materials such as Si, Ge, and Au crystals even though working at very low accelerating voltages in the range of 30 to 60 kV [1]. In this case, a delta-type aberration corrector was designed to simultaneously compensate for third-order spherical aberration (C3,0) and fifth-order 6-fold astigmatism (C5,6).

To avoid beam damage with high energy electron beams, one needs to maximize:
         i) The electron-to-counts conversion efficiency in EELS and TEM/STEM measurements,
         ii) The count rate capacity and collection efficiency in EDS measurements.

 

 

 

 

 

[1] Takeo Sasaki, Hidetaka Sawada, Fumio Hosokawa, Yuji Kohno, Takeshi Tomita, Toshikatsu Kaneyama, Yukihito Kondo, Koji Kimoto, Yuta Sato, and Kazu Suenaga, Performance of low-voltage STEM/TEM with delta corrector and cold field emission gun, Journal of Electron Microscopy 59(Supplement): S7–S13 (2010).

 

 

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