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Moy 0p, Nanoanalytical investigations of Functional Materials by Transmission Electron 
Tih ly, Microscopy 
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“ration, In- Klaus Wetzig and Jiirgen Thomas 
TON 1S there. Institut fiir Festkrper- und Werkstofforschung Dresden 
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Wn levels out 1. Introduction 
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smoothes the Modern transmission electron microscopes (TEM) make it possible to get not only micrographs but 
{nition between also nanoanalytical results from the sample. An important prerequisite for the development of an 
may be different analytical TEM was the scanning transmission electron microscope (STEM), where the specimen is 
the whole parti- scanned in a raster point-by-point with a small electron probe (1). Although its lateral resolution 
anal properties does not exceed 0,5 nm, the STEM became a powerful tool because of the possible combination 
with analytical techniques as microdiffraction, energy-dispersive X-ray spectroscopy (EDXS), and 
electron energy loss spectroscopy (EELS) (2). Such an instrument is called analytical transmission 
electron microscope (ATEM) and it was first constructed in the seventies (3). 
~Lsme 2. Features of the Analytical Transmission Electron Microscope 
The ATEM offers the possibility to get simultaneous information on morphology, microstructure, 
phase and element analysis of sample details in the nanometer range, as summarized in Table 1. 
„Publication component STEM electron “Ss E5LS 
diffraction 
wo 1996) 18 technique imaging diffraction spectroscopy 
11 Solid Films 3 . 
information morphology crystal structure element analysis 
lateral resolution Smin = 0,5 nm Omin = (2.5) nm dpmin = (2...5) nm min = 1 nm 
16. Sci. Techn, mmmum — ) 
detectable limit few unit cells 10° ... 10” atoms few atoms 
0. Warez. Table 1: Analytical information in an ATEM 
2560 By changing lens excitations an electron microdiffraction image is produced on the viewing screen. 
y and It applied It gives structure information on a microregion of only few unit cells. Chemical analysis is possible 
ret 1997 by spectroscopic signals. Their detection is realized by an energy dispersive X-ray detector and by a 
magnetic sector field spectrometer (Figure 1). The lateral resolution of these methods is also in the 
nanometer range, whereas the minimum detectable limit reaches down to few atoms or unit cells 
(4). Most of the analytical TEM work in the STEM mode, that means the information is given in a 
pixel manner. By this, in a simple way point analyses, line scans, and two-dimensional element 
concentration profiles, so called mappings, are possible with all analytical signals. 
HDX! | 
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