ABSTRACT
INTRODUCTION Scanning transmission electron microscopy (STEM) was invented by Baron Manfred von Ardenne at Siemens in 1938 (1), 6 years after the invention of the first transmission electron microscope by Knoll and Ruska in 1932 (2), and its resolution was lower than that of transmission electron microscope at that time. The STEM technique did not well develop until Albert Crewe developed the field emission gun (FEG) at the University of Chicago. Crewe and coworkers demonstrated the ability to visualize single, heavy atoms with their scanning transmission electron microscope in 1970 (3). However, atomic resolution chemical analysis by using the STEM was not reported until 1993 (4,5). Now, STEM has become an essential tool for material characterization, with the highest spatial resolution among all analytical techniques.
