Electron Microscopy, Nanoscopy and Scanning Micro- and Nanoanalysis
Vladimir P. Oleshko, Renaat Gijbels, Severin Amelinckx
The paper considers history and stages of development of electron microscopy (EM) and scanning microanalysis, including theoretical aspects of electron beam-solid interactions, instrumentation, methodology of particular techniques and image analysis, sample preparation and some typical applications as well. Major classes of EM techniques, i.e., stationary beam (transmission) and scanning beam EM methods, analytical electron microscopy (AEM), in situ EM, holography and tomography are overviewed. In AEM several imaging, diffraction and analytical modes are integrated in a design to provide analytical synergism having obvious advantages over any single instrument. The subject of EM is to determine the morphology, crystallinity, defect structure, phase and elemental compositions and electronic properties of a material using the focused electron beam and signals generated in the course of its interaction with the specimen. Various electron-specimen interactions generate a great deal of structural and analytical information in the form of emitted electrons and/or photons and internally produced signals, such as elastically and inelastically scattered electrons, Auger electrons (AE), X-rays, and cathodoluminescence (CL), which can be analyzed in different operating modes. Imaging of transmitted solid materials is essentially due to elastic scattering (diffraction) of electrons by the periodic arrangement of atoms in crystals (diffraction contrast) and/or interference of several diffracted and transmitted beams (phase contrast). High-resolution imaging in scanning transmission mode is possible by using incoherently scattered electrons (Z-contrast). Inelastic interactions are forming the basis for all chemical analytical techniques (energy-dispersive and wavelength-dispersive x-ray spectroscopy, electron energy-loss spectroscopy/energy-filtering transmission electron microscopy, AE and CL spectroscopy).