Scanning Transmission Electron Microscopy (STEM) is a powerful imaging technique used in the field of microscopy to observe the composition, structure, and behavior of materials at the atomic level. STEM combines the principles of traditional transmission electron microscopy (TEM) and scanning electron microscopy (SEM), providing both high-resolution imaging and the ability to analyze the chemical composition in a sample.
In STEM, a beam of high-energy electrons is focused onto a sample, which may be a thin section or a small particle. The electron beam interacts with the sample, and the transmitted and scattered electrons are collected by a detector. The STEM detector scans the focused electron beam across the sample in a raster pattern, pixel by pixel, providing information about the various properties of the material.
One of the key advantages of STEM is its ability to form high-resolution images, surpassing the resolving power of light microscopy. This is achieved by using a high-energy electron beam, which has a much smaller wavelength than visible light. Furthermore, STEM allows for the simultaneous collection of different signals, such as secondary electrons, backscattered electrons, and characteristic X-rays, offering valuable insight into the sample's composition and morphology.
STEM finds applications in various fields, including materials science, nanotechnology, biology, and chemistry. It enables scientists to investigate the structure and behavior of materials at the atomic scale, helping to understand their properties and guide the development of new materials with improved properties. The technique has contributed significantly to advancements in fields such as semiconductor technology, catalysis, and biomaterials.
