Investigations on thin solid layers by analytical transmission electron microscopy

Abstract

Among the instruments for solid state characterization working with a free electron probe, the Transmission Electron Microscope (TEM) has the best lateral resolution. The application is restricted, however, by the demand that the samples need to be suitably thinned. TEMs operating in the scanning mode yield several advantages. Equipped additionally with spectrometers, the TEM becomes an Analytical TEM. Energy Dispersive X-ray Spectroscopy (EDXS) and Electron Energy Loss Spectroscopy (EELS) allow the chemical analysis of the observed details of structure; the EELS permits additionally investigations on the electron configuration and on binding relations. Technical developments have increased considerably the information possibilities, such as lateral resolution or detection sensitivity. Recently two new types of instruments are in development, the dedicated Scanning-TEM with a field emission gun, supplying scanning images and analyses up to the nanometer range, and the energy filtering (stationary beam-) microscope which yields images and diffraction diagrams with a sharpness in contrast not previously reached. In the future the construction of an “aberration-free” objective lens promises a further advance into the atomic dimension.