An analytical electron microscope equipped with a side-entry goniometer
(SEG) has recently become more widespread than a conventional electron
microscope by the following reasons: (1) a variety of specimen holders, (2)
large tilting angle with eucentricity. However, the resolution of SEG-system
is about 0.4 nm, whereas the resolution of 0.25 nm or less can be obtained
by an electron microscope equipped with a top-entry goniometer
(TEG)1).
Factors determining the resolution of an electron microscope are (1) the
aberration coefficients of the objective lens, (2) stability of exciting
currents, (3) illumination angle of the electron beam on the specimen, (4)
energy spread of the electron beam, and ( 5) vibration and specimen drift.
It has been usually difficult to observe high resolution images during use
of the SEG system, because of the aberration coefficients of the objective
lens, vibration and specimen drift. In order to obtain a resolution of less
than 0.3 nm with SEG system at 200 kV, both of spherical and chromatic
aberration coefficients should be reduced less than 2 mm. Moreover, relative
amplitude of vibration between the specimen and pole pieces should be less
than a half value of resolution limit. The image drift should be less than
0.02 nm/sec, because the exposure time usually required for photographing a
high resolution image is about 5 second.
Atomic-Scale Structure Investigation of CeO2/YSZ/Si Hetero-Interface by High Resolution Analytical Electron Microscope
