The preparation of interfaces for TEM investigation is inherently prone to the production of artifacts. In some cases it is possible to avoid potential hazards in the interpretation of high-resolution images by creating the interfaces in pre-existing, thin, TEM specimens so that no further preparation is required. As an example of this approach, results from a study of interfaces produced by the heat-treatment of iron-bearing olivine TEM samples are presented. Image simulations are presented which show that even in these favorable situations, the greatest care must be taken in interpreting image contrast at interfaces in high-resolution electron micrographs.

Commercial pure y Faujasites were intetchanged with several metallic ions, in order to improve catalytic properties. The resulting samples were studied using a series of physicochemical techniques and catalytic tests were realized some results are reported in this work.

Starting from electron microscope high resolution images we apply the technique of digital image processing to analyze some structural properties of oxides. We identify the structural features in the images that give origin to the diffuse scattering observed in the electron diffraction patterns of these oxides. We obtain results for three different systems: YBaCuO and BiSrCaCuO high temperature superconductors and mullite (type germanate). The analysis and enhancement of the images is done by filtering them in their Fourier space.

A structural investigation of the Ru-RuOx/TiO2 catalyst was carried out in order to determine the role played by the support, the size of the particles, their dispersion, structural relationship with the support and the preparation conditions on the activity. In the ideal catalyst the metallic particles are 10–15Å in size. Moreover they are selectively dispersed on the TiO2 crystallites with the rutile structure. This uneven distribution is not found for other metals ( Rh, Pt, Co, Ni, etc...) on P25 though the preparation procedure was similar.

We present here experimental results using High Resolution Electron Microscopy (HREM), of the structure and behavior of gold clusters on magnesium oxide smoke particles. These indicate that there is a strong interaction between the particle and the substrate, and under electron beam irradiation the particle can immerse completely into the substrate. Various other observations, for instance, motion of twin boundaries, volume shrinkage and surface diffusion, faceting etc., confirm the basic structural instability of small particles. Initial results also indicate that the stability of the cluster depends on particle size, the irradiation flux and the nature of the substrate.

A series of Mo/Si multilayer films (MLF) has been fabricated by e-beam evaporation onto (100) silicon substrates at substrate temperatures (Ts) in the range of 300 to 600K, with deposition rates varying from 0.5 to 3Å/s. The quality of the samples fabricated at 525K≤Ts≤575K with a deposition rate of 1Å/s was found by high-resolutlon electron microscopy to be comparable to that of sputtered films. The major differences between the structures of the e-beam evaporated samples and the sputtered ones were that the thicknesses of the Mo on Si interfaces were larger, and the Si on Mo interfaces were smaller, for the e-beam MLF.

High-resolution transmission electron microscopy has been utilized to critically assess semiconductor-based epitaxial films and interfaces. These results then provide a sound, scientific basis for subsequent process modification. Materials optimization is therefore achieved more efficiently.

Determination of the bonding configuration at the epitaxial CaF2/Si(111) interface has revealed Ca-Si bonds in the interfacial plane. Removal of an unstable layer of F from the interface occurs during a rapid thermal anneal. In comparison, the CaF2/Si(100) interface is not smooth, making assignment of interface bonding configurations ambiguous. After a rapid thermal anneal, evidence for an intermediate interfacial phase is observed on Si (100). This phase does not occur on Si (111).

A series of sputtered tungsten-carbon multilayer structures with periods ranging from 2 to 12 nm in the as-prepared state and after annealing at 500°C for 4 hours has been studied with high resolution transmission electron microscopy. The evolution with annealing of the microstructure of these multilayers depends on their period. As-prepared structures appear predominantly amorphous from TEM imaging and diffraction. Annealing results in crystallization of the W-rich layers into WC in the larger period samples, and less complete or no crystallization in the smaller period samples. X-ray scattering reveals that annealing expands the period in a systematic way. The layers remain remarkably well-defined after annealing under these conditions.

The morphology and crystal structure of diamond crystallites grown by radio frequency (RF) and microwave (MW) plasma enhanced chemical vapor deposition (PECVD) under comparable conditions are examined by electron microscopy and found to be a strong function of the plasma. A novel TEM sample preparation method is developed to examine the internal structure of diamond as well as interfacial structure between diamond and substrate by direct deposition of diamond crystallites on prethinned metal grids. The diamond crystallites grown by RF PECVD are highly defective and composed of nanocrystalline grains of random orientation while those grown by MW PECVD are wellfaceted and process near perfect long range order in crystal structure.

HREM was used to investigate the microstructure and bonding configuration at the interface between TiSi2 and Si (111). The interpretation of the micrographs requires extensive image calculations which were carried out for the first time on this very complex silicide/silicon system. Four different interface models are presented and the corresponding computed interface images are compared with the experimental image. Contrast analysis shows that a model in which a final plane of Ti abuts a layer of Si with a configuration typical of bulk Si best matches the observations. Moreover, the presence of Ti at the interface seems to stabilize a terminal plane of Si with triple dangling bonds.

Recent molecular beam epitaxy (MBE) studies have shown that depending on surface conditions of GaAs two different growth modes, layer-by-layer or island, occur at the initial stage of the growth of ZnSe on (100) GaAs. In this study, we have observed various types of GaAs surfaces used for the MBE growth of ZnSe by reflection electron microscopy and ZnSe islands on a GaAs substrate by cross-sectional high resolution electron microscopy. Results of these observations suggest that the occurrence of two growth modes is determined by atomistic structures of GaAs surfaces such as the surface stoichiometry or the density of atomic steps.

Microstructural studies of Si precipitated on contact holes through Al-Si alloy has been carried out for 1-Mbit DRAMs using cross-sectional transmission electron microscopy and X-ray microanalysis. Lattice images reveal the perfect epitaxial growth of Si on Si substrates at contacts through Al-Si alloy at temperatues ≤420°C. At the interface between substrates and the solid-phase epitaxial Si, ellipsoidal micro-defects, associated with amorphous oxygen-rich materials containing Al, are observed. In the epitaxial Si evidence of dislocations and twins is found.

High resolution electron microscopy lattice images were calculated for six atomic arrangements at the CoSi2 – (111)Si interface i.e. type A and type B, each type with Co atoms at the interface 8-, 7- and 5- fold coordinated. The results suggest that the new 8-fold coordinated variant should be easily distinguishable from the 5-fold coordinated variant, while 8- and 5-fold coordinated variants should be discernable from the 7-fold coordinated variant by the observation of a relative rigid body translation of Si and CoSi2 lattices. Unit cell size variation was found not to affect the contrast in the computed images of the interface provided that (i) the unit cells were chosen correctly i.e. to assure continuity of the periodic extension and (ii) the sampling point density was sufficient to prevent aliasing.