Scanning Transmission Electron Microscopy (STEM)

In STEM, a tiny, convergent electron beam is scanned over a defined area of the sample. At each spot, the generated signal is simultaneously recorded by selected detectors, building up an image. Furthermore, such a convergent beam is used to gain a highly localized signal from the specimen in analytical TEM (e.g., EDXS, EELS), and thus the combination of STEM with analytical methods is a main application in practical work. As the resolution of a STEM is limited by the diameter of the electron beam, the correction of the spherical aberration of the probe-forming lens leads to substantial improvements of the imaging properties and gives access to the sub Angstrom regime (see here).

Utilized signals: elastically scattered electrons - direct and diffracted beams (BF/DF) and incoherent scattering (Z contrast)