High-angle annular dark-field imaging on a TEM/STEM system
High-Angle Annular Dark-Field (HAADF) imaging is a technique that brings out compositional contrasts with a sensitivity about 106 times higher than X-ray images, thereby allowing image recording in normal STEM exposure times (a matter of minutes) instead of the time required for X-ray images (usually several hours). The technique uses those electrons that have undergone high-angle scattering. These have Z dependence and are therefore very effective in bringing out compositional contrasts.Much of the HAADF work to date has been performed on dedicated STEMs. However, the technique can be performed as well with the annular Dark-Field detector on several types of TEM/STEM systems. Such systems have the added advantage of camera-length flexibility, providing a range of images with different kinds of information from the same detector.