Contrary to most classical adhesion test, the blister test provides quantitative adhesion energy measurements. We demonstrate its application to 1 mu m thick W films in tensile stress state deposited by xenon DC magnetron sputtering on PECVn/Si(100) substrates. The W films surface morphology; structure and residual stress were also characterized by atomic force microscopy, X-ray diffraction and substrate curvature measurements as function of the deposition pressure. Films characteristics are compared with those of W films deposited directly on Si(100) substrates.
A new method is described for analysing variations in structure from high resolution electron microscope images. In Fourier theory, the image of a perfect crystal can be considered as the sum of sinusoidal lattice fringes having constant amplitude and phase given by the corresponding Fourier component. Imperfections are introduced by allowing these Fourier components to be a function of position, thus combining real space and reciprocal space information. It is shown how images can be obtained of the local value of the amplitude and phase of each major image periodicity. The amplitude and phase images are interpreted in terms of image detail and structural variations. Relationships are derived between the phase images and displacement fields due to a distortion of the lattice fringes and variations in the local reciprocal lattice vector. The meaning of the amplitude and phase images is illustrated by the analysis of experimental images of antiphase boundaries. Quantitative analysis of experimental images of carbon nanotubes is carried out using amplitude images and of strained metal multilayers using phase images.
The composition, morphology and Volume fraction of the metastable T' phase formed in an industrial Al-4.91wt%Mg-3.20wt%Zn alloy have been investigated using the tomographic atom probe. Roughly globular and sometimes elongated T' precipitates are present in the alloy aged at 140 degrees C for 24 hours after solution heat treatment and water quenching, with a number density of 1.8 x 10(17) cm(-3). The volume fraction of the phase is close to 4.5%. The T' precipitates were found to have an average composition of 37.5 at% Mg, 36.5 at% Al and 26 at% Zn, which is, within experimental error, identical to that of the stable T phase Mg-32(Al,Zn)(49).
High resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) have been used to investigate plasmon losses of aluminum nanospheres. A model based on the dielectric theory allows to attribute the observed features in the loss spectra of particles of different size to either surface or volume losses. Both, surface and volume loss peak, show size dependent characteristics which are reproduced by this model. EEL spectra with negligible surface loss contributions can be used to determine the dielectric function of the observed material by means of the Kramers Kronig relations. For the case of non negligible surface contributions we introduce the notion of dielectric signature. This dielectric signature allows to study the transition where surface effects start to become visible in the spectra. Our analysis suggests that for a system of known composition this approach is a useful tool to determine the importance of surface effects.
It is known that high resolution electron microscopy can provide quantitative information on the nature of crystalline materials. In the present paper an image processing technique is introduced that profits from long extinction distances in electron diffraction. It is applied to study the real structure of spinel films, which were grown on MgO substrates by solid state reactions. The simulation of electron diffraction and the analysis of calculated contrast tableaus revealed that the intensity of the spinel-specific {220} reflections is a monotonous function of the crystal thickness in a wide range of parameters. Making use of this relation experimental micrographs of spinel films and MgO/spinel interfaces are interpreted by Fourier filtering. First, it is the aim of the technique developed to map the local thickness of spinel films by evaluating the {220} related contrast. Second, if the specimens are sufficiently plane, the degree of abruptness of the different spinel/MgO reaction fronts can be analysed.
A method for shape reconstruction and extraction from objects that have a certain regularity but are observed in a scanning electron microscopy image with some degree of overlap is presented. The proposed algorithm first calculates the curvature at each contour point of the object in the digitized binary image in order to detect the vertexes. Reconstruction of the shape of overlapping objects is then based on geometrical considerations using the information from the vertex co-ordinates. The procedure is independent of the size and orientation of the objects. The method is applied to the shape reconstruction of partially overlapping tabular silver halide microcrystals.
Due to its mechanical properties and low density, the Ti-6Al-4V titanium alloy is used in hip prostheses. But the tribological behavior of Ti-6Al-4V sliding against ultra high molecular weight polyethylene involves wear degradations. The wear behavior of (Ti-6Al-4V/UHMWPE) couple can be improved by ion implantation of nitrogen. After a characterization study to find the optimal parameters for classic ion implantation, this study presents an analysis of wear behavior in comparison with chemical composition, microhardness and adhesion work for a new implantation technique, plasma immersion ion implantation.
Experimental distortion profiles have been measured in strained Au/Ni MBE multilayers using a quantitative analysis of the HREM micrographs. In order to study the reliability of these measurements, similar analysis have been made on simulated HREM images of Au/Ni interfaces. It is found that the measured profiles are reliable only on a limited range of experimental conditions i.e. microscope defocus and specimen thicknesses. Furthermore, it will be shown that the presence of a mixed layer introduced by the ion beam thinning on both sides of the cross section specimen affects considerably the shape of the strain profile recorded on thin areas.
The Si/Au system has been intensively studied for its application in the field of microelectronics. This paper presents results obtained on segregation and interaction phenomena in such a system for a range of temperature below the eutectic (363 degrees C). Investigations were performed using two complementary techniques: Auger Electron Spectroscopy (AES) and Transmission Electron Microscopy (TEM). The importance of the microstructure on the segregation phenomenon is shown. Indeed, the driving force of the gold/poly-silicon system evolution is silicon recrystallization followed by superficial silicon segregation on silicon-gold mixture even at very: low temperatures.
An electron scattering model called IntriX associated to electron X-ray emission spectrometry (EXES) at high resolution is tested to characterize stratified samples. The ability of the model to simulate the X-ray intensity emitted by a surface layer and a buried layer in film/substrate systems is illustrated. The characterization of Al/Mn/Si multilayers by means of non destructive techniques (electron probe microanalysis (EPMA), Rutherford back scattering (RBS)) have been performed comparatively to the EXES measurements. The potentialities of the IntriX model combined to EXES to predict thicknesses is established by comparison with EPMA and RBS results.
Two alkali aluminoborosilicate glasses containing oriented crystalline particles have been investigated by Transmission Electron Microscopy (TEM). Both materials have been thermally treated in order to phase-separate crystalline droplets and have been then redrawn at a temperature above their softening point to elongate and orient them. In one sample the crystalline phase is a Ag(Cl, Br) solid solution, which gives the material birefringence properties, while in the other sample the particles on the surface have been chemically reduced to Ag, giving the material polarizing properties (Polarcor (TM)). Most of the observed needle-like particles are built up by a small number of well grown crystallites often separated by voids. Both the crystallites and the voids occupy the whole width of the particles and can assume very different lengths. Crystallites inside a particle have different orientations.
The concept of Fourier Transform has been extensively used for decades in spectroscopy as well as in image science. This should not overshadow the work of G. Lippmann. This scientist applied Fourier techniques as early as 1894 to give a full theory of his photographic process of color encoding. Lippmann's expanation calls for temporal frequencies; conversely, Duffieux's works relies on spatial frequencies.
We present the first results of a combined scanning tunneling microscopy (STM) and surface X-ray diffraction (SXRD) study of Ag monolayer deposited on Cu(111). The STM images of Ag monolayer show a periodic frame of triangles, 4 or 5 atomic row wide with 1 or 3 atoms protruding in the centre respectively. Away from the triangles, the corrugation of the atomic rows is about 0.05 Angstrom while the depth of the triangles is about 0.5 Angstrom. SXRD shows an "average" Ag surface unit cell (9.43 x 9.43) times the Cu(111) surface unit cell without rotation in good agreement with STM observations.
Depth resolution in SIMS profiling of multilayers Co/Cu/Co and Cu/Co/Cu samples has been estimated as a function of bombardment parameters with 3 keV O+2 ions. The best depth resolution is obtained at normal incidence. At glancing incidence it is necessary to flood with oxygen to improve the resolution. Topography development due to sputtering, accountable for worsening of profiles, is reduced by oxygen implantation either directly by O+2 at normal incidence or by flooding at glancing incidence.
Physicochemical interactions at, Cu-MgO buried interfaces are studied by electron X-ray emission spectroscopy and compared to results obtained for native interfaces. The atomic arrangement is also determined. The role of the characteristics of the substrate is evidenced. Results suggest that weak or strong interactions can je present at the interfaces.
Depth profiling analysis by AES combined with ion sputtering is employed for the characterization of Co-Cu multilayer interfaces prepared either by RF sputter deposition or by electrodeposition. Depth concentration profiles are derived from Auger profiles with appropriate corrections of elemental sensitivities, escape lengths of Auger electrons and from changes of the sputter rate occuring at interfaces with composition; they are expressed as atomic densities which can provide significant atomic balances, film thicknesses and depth resolution measurements, Microroughness induced by sputtering is widely improved by the Zalar rotation method during etching, so the remaining contribution (7-10 nm) to the interface broadening mainly consists with atomic mixing whereas important resolution losses (Delta Z > 20 nm) observed in electrodeposited layers as well as in sputtered materials at Co-->Cu interfaces can be attributed to the sample preparation rather to the sputtering process itself.
Bimetallic particles of PdCu and PdCu3 are prepared by decomposition of organometallic compounds on MgO micro-cubes. During the annealing between 350 and 400 degrees C, in reducing atmosphere, PdCu particles grow with the fee structure, without defined shape. The particles epitaxially (001) oriented on MgO are dilated and accommodated to the substrate. After annealing at 450 degrees C, the particles adopt the beta ordered structure. The particles are limited at the edges by (100) and (110) faces. Most of them are oriented (001) on MgO with [110]PdCu parallel to [100]MgO, which corresponds to a perfect accommodation of the lattices without deformation compared to the bulk, despite of the reduction in H-2. The PdCu3 particles smaller than about 10 nm were found with the alpha ordered structure, without periodic anti-phase boundaries.
Stress in thin films deposited by Reactive Low-Voltage Ion Plating (RLVIP) is studied in air and at room temperature. A multilayer stack, composed of tantalum pentoxide and silicon dioxide layers, is considered and the interactions layer to layer turn out to have no effect as regards to the final bending. The evolutions of plate bending after annealing show the possibility to reduce the stress as well as the absorption for tantalum pentoxide thin films. Finally, ion implantation, with ions such He+ or Xe+ accelerated at energy in the MeV range, proves to be also a way to vary and reduce the stress in thin films.
When wetting is complete, coherent epitaxies on a thick planer substrate B build up z continuous pseudomorphous layers A which are fully strained according to their natural misfit m. The so-accumulated strain energy density is responsible for some remarkable facts: 1) Each layer is formed at precise undersaturation. At saturation there is a specific number of wetting layers z(0). 2) Such layers accumulate strain energy and then may relax plastically by interfacial dislocations at a critical thickness z(d1). 3) At some other critical thickness z(SK), (z(0) < Z(SK) < Z(d1)): the monolayer growth becomes less stable than layer thickening, what leads to three-dimensional (3D) islanding on the z(sk) wetting layers, called Stranski-Krastanov (SK) growth. Such islands laterally relax and, since coherent with their substrate, drag the substrate which relaxes too. 4) If the equilibrium shape ratio r of non misfitted 3D deposit (m = 0) depends on the wetting, for a misfitted (m not equal C)) and relaxed crystal, the strain opposes to wetting, so that the higher the elastic energy, the greater the shape ratio r(m). 5) Since the equilibrium shape of a 3D crystal depends upon strain, at each dislocation entrance the shape ratio of the crystal varies in a sudden way.
