Beam heating of a moderately thick cold stage specimen in the SEM/STEM

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Abstract
SUMMARY: A mathematical model for the electron beam heating problem of thick specimens (thickness less than the electron range) in the cold stage of SEM/STEM is proposed, and an analytic solution for the problem is provided. The use of the model is demonstrated by calculating the maximum temperature rise in a red blood cell mounted on a metallized polymer film, for a large range of operating conditions. With a probe size of 20 nm and probe current of less than 10 nA the temperature rise was found to be on the order of 5 K. This temperature rise increases proportionally to the probe current if all other variables are kept constant. Although the amount of energy dissipated in thick specimens is large relative to thin films, temperature rise can be minimized by mounting the thick sample on a metal stub or on a metallized film thus providing large heat transfer area through a high thermal conductivity substrate. Of course our calculations only have meaning if the specimen is in good thermal contact with the underlying support.