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Double crystal diffractometry and topography are now routinely used in many laboratories for the inspection of epitaxially grown devices. However the trend towards thinner layers and more complex structures requires the continued development of novel approaches using these techniques. This thesis is concerned with the development of these approaches to study the structural uniformity of semiconductor materials. The uniformity of large single crystals of lithium niobate has been studied using synchrotron radiation and double crystal X-ray topography. This study has shown a variety of contrast features including low angle grain boundaries and non-uniform dislocation densities. The abruptness of an interface between a layer and the underlying substrate has been studied using glancing incidence asymmetric reflections. Comparisons to simulated structures revealed that a closer match was achieved by the inclusion of a highly mismatched interfacial layer. This study illustrates the need for careful comparison between experimental and simulated rocking curves as different structures may produce very similar rocking curves. A double crystal topographic study of a AlGaAs laser structure revealed X-ray interference fringes. These are shown to be produced from the interaction of two simultaneously diffracting layers separated by a thin layer. Possible formation mechanisms have been discussed showing that these fringes are capable of revealing changes in the active layer at the atomic level. A novel approach has also been developed using synchrotron radiation to study the non-stoichiometry of GaAs. This approach uses the quasi-forbidden reflections which are present in III-V semiconductors due to the differences in the atomic scattering factors. This study has also discussed the behaviour of strong and weak reflections in the region of absorption edges and modelled their behaviour using the anomalous dispersion corrections of Cromer and Liberman.

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There is a growing demand to obtain XPS analyses from increasingly smaller sample areas. The development of a Transmission X-Ray Photoelectron Spectrometer (TXPS) will allow spectrum acquisition and imaging with a lateral resolution approaching 1 mum2. The principle is based on back-foil excitation where thin samples are placed on an aluminium foil or have an evaporated source backing. Electron irradiation of the foil produces characteristic X-rays locally and this, in turn, gives rise to a small source of photoelectrons from the opposite side of the sample. Rastering the electron beam scans the X-ray interaction volume which allows imaging. Photoelectron lateral resolution is dependent on the sample and foil thicknesses and is determined by the width of the X-ray excitation envelope and on the electron beam diameter. In this work a VG Scientific MA500 is modified to give the ideal 180° geometry for TXPS. A hemispherical analyser with an extended high magnification transfer lens ensures a large solid angle of photoelectron collection, and the hemispherical analyser gives the (previously unobtainable) energy resolution necessary to obtain chemical state information. Aspects unique to TXPS spectral and image interpretation are described. The analysis conditions where sample damage is likely are investigated. Photon induced damage is manageable, but is shown to be far more of a technique drawback than Joule heating. Specimen charging presents no particular problems, although it can be both positive and negative in TXPS. It is believed that TXPS is the ideal way of examining ultramicrotomed sections through interfaces and soft composite materials. Harder materials, such as ceramics and metals, require ion beam thinning in a similar way to TEM specimens. Specimen production needs are addressed as well as the problem of making the TXPS technique far more routine to the analyst. A magnesium/aluminium alloy is ion beam thinned to demonstrate TXPS from a harder material. The interlayer between a chlorine containing latex and mild steel is also analysed by TXPS, following the removal of the bulk substrate and ultramicrotomy. Data are examined and an iron valence state change across the interface allows conclusions to be drawn about the continued growth of the protective interphase under environmental exposure.

A number of alloy bars were manufactured to some very precise specifications. Certain scientific institutions then performed chemical analyses and made several measurements of the content of some chemical elements of interest. The measurements made on each of the alloy bars can be considered a set of repeated measurements. Modelling techniques for repeated measurements are now well established. Many of these techniques are based on the multivariate normal distribution with some specified mean and covariance structure. Modelling of the covariance structure is necessary so that efficient and meaningful inferences may be made about the mean structure. For the example of repeated measurements made on an alloy bar, the set of measurements is assumed to follow a multivariate normal distribution with a mean mu and a covariance structure Sigma. The choice of mu and Sigma is explored. Experiments which produce sets of repeated measurements can quite often result in a large amount of data being collected. This means that the use of statistical techniques to fit the model to the data can become computationally demanding. The use of maximum likelihood estimation is considered. Several aspects of constructing computationally efficient algorithms to maximise the likelihood function of the data are addressed. When the proposed model has been fitted to the data the suitability of the model and its assumptions are investigated. A score test is constructed to assess the correctness of the proposed covariance structure. Normal plots of the standardised residuals are used to assess other possible defects in the model, such as an incorrect assumption of normally distributed data. The work which has been carried out was motivated specifically by experiments where the set of repeated measurements came from a chemical analysis of an alloy material. It is the percentage content of a number of chemical elements which is of interest and the choice of statistical models was made with this in mind. However, it is demonstrated how the statistical techniques and models for the analysis of the chemical data may be used to analyse repeated measurements which arise from other kinds of experiments.

Dans cette étude est proposée une méthode de description exhaustive d'une microstructure 2D et 3D afin d'en extraire des composantes morphologiques pertinentes qui seront la base d'une triangulation surfacique. Nous proposons cette structure triangulaire morphologiquement optimisée comme base d'entrée d'un des nombreux codes commerciaux de maillage qui utilise comme source d'entrée une description vectorielle d'une image 2D ou une triangulation surfacique d'une image 3D. Ces outils de maillage seront utilisés dans le cadre d'un calcul élément fini afin dévaluer la pertinence morphologique de notre triangulation. Les descripteurs morphologiques d'une image 2D sont simples et exhaustifs. Ils permettent l’application de la triangulation de Contrainte de Delaunay dans les cas bi et multiphasé. En 3D, le cas biphasé diffère du cas multiphasé. Dans le cas biphasé, nous étudions les limites de la morphologie mathématique dont les outils peuvent encore être utilisés dans quelques étapes de la triangulation comme la définition de surface des objets dans l'image. La triangulation proprement dite sera réalisée par des outils morphologiques originaux. Dans le cas multiphasé, les descripteurs morphologiques ne sont plus définissables simplement et uniquement par les outils morphologiques classiques; l'établissement de nouveaux concepts mathématiques, donnant lieu à des propositions et parfois à des preuves, est nécessaire. Ces nouveaux outils vont nous permettre à la fois de réaliser une description fidèle des composantes de l'image, mais aussi de proposer une méthode originale de triangulation de ces surfaces. / In this thesis, a complete description method of 2D and 3D microstructures is proposed in order to extract pertinent morphological components which will be the base of a superficial triangulation. We propose this morphologically optimized triangular structure as an entry basis of one of many commercial meshing codes which use a vectorial description of a 2D image or a superficial triangulation of a 3D image as an entry basis. These meshing tools will be used in the framework of finite element calculations in order to evaluate the morphological pertinence of our triangulation. The morphological descriptors of a 2D image are simple and complete. They allow the application of Constrained Delaunay Triangulation in the case of bi and multiphase. In 3D, the biphasic case is different to the multiphase case. In the biphasic case we study the limits of mathematical morphology whose tools can still be used in some stages of the triangulation like the definition of the surface of the objects in the image. The triangulation will be carried out using original morphological tools. In the multiphase case, the morphological descriptors cannot be defined simply and exclusively by classical morphological tools; the establishment of new mathematical concepts, giving way to propositions and sometimes evidences are necessary. These new tools will allow us to carry out a correct description of the components of the image and to propose an original triangulation method of these surfaces.

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