Properties of a semiconductor are determined by its structure on the atomic level, for example by point defects. Using EDS mapping at the highest possible resolution it is possible to locate and characterize such defects.
This application example looks at data kindly provided and published by M. W. Chu (M. W. Chu et. al., Phys. Rev. Lett. 104, 196101 (2010), https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.104.196101). Investigated was a multi-layer structure consisting of alternating layers of InGaAs and InAlAs. Using only 3 ms dwell time (13 s total measurement time) and 33 pA beam current, it was possible to determine an In composition variation in one atomic column of the InGaAs structure. The absence of In can be seen by the missing blue color in the lower right corner of the In map, it also causes the lower InGa column in the HAAD line profile shown.