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A combination of the 'semi-empirical' model for secondary electron production and the TRIM routines which describe ion stopping power, scattering, and transport, has been used to construct a Monte Carlo simulation (IONiSE) that can quantitatively interpret the generation of secondary electrons (SE) from materials by fast helium ions. This approach requires that the parameters of the semi-empirical model be determined by fitting to experimental yield data but has the merit that, unlike more fundamental models, it can be applied with equal ease to both pure elements and complex compounds. The application of the model to predict the topographic yield variation of helium generated SE as a function of energy and material, and to investigate the ratio between SE generated by incident and backscattered ions, is demonstrated.

An electron holographic method is introduced for the study of ferroelectric domain walls. The method allows not only direct imaging of the domain wall but also the measurement of local spontaneous polarization. Preliminary results of first high-resolution imaging of ferroelectric domain walls by using this technique in BaTiO3 and quantitative measurements of electrostatic field distribution across domain walls are presented.

The electron-optical parameters required to generate an electron hologram are discussed. It is shown that the new generation of commercial field emission transmission electron microscopes (FEG TEM) meet the conditions required. Practical details of the procedures to set up and record a hologram are described. The steps necessary to reconstruct the hologram are also discussed and an outline is provided of a program for the Apple Macintosh™ personal computer which implements these operations. The integrity and accuracy of the reconstruction program has been tested by means of a detailed simulation of high-resolution holograms starting from dynamical multi-slice calculations of the exit wavefront.

Recent advances in instrumentation have produced the first commercial examples of what can justifiably be called high-resolution scanning electron microscopes. The key components of such instruments are a cold field emission gun, a small-gap immersion probe-forming lens, and a clean dry-pumped vacuum. The performance of these microscopes is characterized by several major features including a spatial resolution, in secondary electron mode on solid specimens, which can exceed 1 nm on a routine basis; an incident probe current density of the order of 10 6 A/cm 2 ; and the ability to maintain these levels of performance over an accelerating voltage range of from 1 to 30 keV. This combination of high resolution, high probe current, low contamination and flexible electron-optical conditions provides many new opportunities for the application of the SEM to materials science, physics, and the life sciences.

Voltage profiles of the source-drain region of a CMOS transistor with 75nm gate architecture taken from an off-the-shelf Intel PIII processor are presented. The sample preparation using a dual beam system is discussed as well as details of the electron optical setup of the microscope. Special attention is given to the analysis of the reconstructed holograms.

The spatial resolution of the scanning electron microscope is limited by at least three factors: the diameter of the electron probe, the size and shape of the beam/specimen interaction volume with the solid for the mode of imaging employed and the Poisson statistics of the detected signal. Any practical consideration of the high-resolution performance of the SEM must therefore also involve a knowledge of the contrast available from the signal producing the image and the radiation sensitivity of the specimen. With state-of-the-art electron optics, resolutions of the order of 1 nm are now possible. The optimum conditions for achieving such performance with the minimum radiation damage to the specimen correspond to beam energies in the range 1-3 keV. Progress beyond this level may be restricted by the delocalization of SE production and ultimate limits to electron-optical performance.

Plural scattering is a significant limit to the accuracy of ELS quantitation. A simple deconvolution technique, sufficiently rapid for incorporation in an interactive quantitation routine, has been developed. The application of this approach improves the reliability of quantitation and, by yielding edge profiles which are reproducible, makes it possible to use computed (or previously stored) edge shapes for quantitation or background fitting.

Computer control of an electron microscope makes it possible to centralize the display of the important operating parameters, and to make provision for the storage and retrieval of sets of operating conditions. A Vacuum Generators HB5 STEM has been interfaced with a commercial microcomputer to perform these functions. Although fully automatic operation has not been provided, the ease of use of the microscope is considerably enhanced. The same computer can be used to produce special scan rasters, such as vector scans for electron lithography, and to provide a simple, software controlled, image storage system.

In this paper equations which govern the detectable limits in a transmission electron energy loss experiment, where inner-shell edges are used for micro-elemental analysis, are derived. The minimum detectable number of atoms and the minimum mass fraction are evaluated for several model cases, including the variation with spectrometer acceptance angle and accelerating voltage.

The technique of scanning transmission electron microscopy (STEM) has been employed usefully in studies of amorphous materials, and the theory of image formation and interpretation in this case has been well developed. Less attention has been given to the practical and theoretical problems associated with the use of STEM for the examination of crystalline materials. In this case the contrast mechanisms are dominated by Bragg diffraction and so they are quite different from those occurring in amorphous substances. In this paper practical techniques for the observation and interpretation of contrast from defects in crystalline materials are discussed. It is shown that whilst images of defects are obtained readily under all typical STEM operating conditions, the form of the image and the information it contains varies with the angle subtended at the specimen by the detector. If this angle is too large significant image modifications relative to the "conventional" transmission electron microscope case may occur and the resolution of the image may degrade. If this angle is too small, then signal to noise considerations make an interpretation of the image difficult. In this paper we indicate how the detector angle may be chosen correctly, and also present techniques for setting up a STEM instrument for imaging a crystalline material containing lattice defects.