Extracting Quantitative Information from High Resolution Electron Microscopy

Despite the development of high-resolution electron microscopy (HREM) that allows imaging of most materials, the extraction of quantitative information at atomic scale still requires considerable additional efforts. This review presents the recent developments on techniques that can be used to determine the local strain, chemical composition or atomic structure retrieval in HREM. The source of noise in images and effective methods for improving the signal-to-noise ratio in direct or Fourier space are discussed. The artefacts of filtering are commented. In all the methods, the sample thickness has to be determined. A detailed analysis of the thin foil relaxation effect on the measured distortion fields is presented as well as the possibilities of using finite element calculations for its modelling. The local composition measurement based on the chemically sensitive reflections; pattern recognition and the measurement of lattice parameters are described. Examples from semiconductor heterostructures are discussed. The current state of the strategies used for the retrieval of the atomic configuration of defects from HRTEM images is briefly presented. The limits of detection and the accuracy of the methods are summarised; and it is pointed out that electron holography, focal series reconstruction and the coming Cs corrected microscopes will help to obtain this information with better accuracy.