The structures of equal-thickness Co/Re multilayer films and several Co/Re bilayer films have been investigated by X-ray diffraction at low and high angles. Analysis of low-angle reflectivity data from bilayer films indicates that interfacial intermixing is limited to three monolayers and that the two interfacial configurations are different. The high-angle X-ray diffraction data show that multilayer films have coherent interfaces and a highly textured structure with hep [002] orientations normal to the film plane for periods 21 Å ≤ Λ ≤220 Å. Detailed structures have been determined by fitting the X-ray spectra to calculated ones using a trapezoidal model. The results indicate that samples with 42 Å≤ Λ ≤220 Å have relatively sharp interfaces, in good agreement with the bilayer results. In addition, an out-of-plane expansion of the Co (002) layer is observed in samples with large Λ and results from structural disorder leading to a reduced atomic density. For Λ <21 Å the interfaces arise from the rougher surfaces of the deposited layers.

The ability to determine which growth mechanism (interface-reaction-rate-limited vs. diffusion-limited) of intermetallic formation by interfacial reactions using differential scanning calorimetry (DSC) is demonstrated. Suicide formation in multilayered thin films of chromium and amorphous silicon was chosen as a model system. It is shown that suicide formation in this system followed a linear rate law corresponding to an interface-reaction-rate-limited growth mechanism. An activation energy and pre-exponential for the rate constant were determined.

The structural properties of (ZnSe/FeSe) superlattices, grown with and without a ZnSe buffer layer on (001) G a As substrates by molecular beam epitaxy, have been studied by transmission electron microscopy. High quality (ZnSe/FeSe) superlattices are obtained when grown on a ZnSe buffer layer on (001) GaAs substrates. In contrast, nominal (ZnSe/FeSe) superlattices grown directly on (001) GaAs substrates without a buffer layer showed evidence for intermixing of the layers in the superlattice indicating that the superlattice is unstable. We observed a disordered structure and an ordered structure in the resulting Zn1−xFexSe solid solution. The ordered structure corresponds to chemical ordering of Zn and Fe atoms along the < 100 > and < 110 > directions. We have studied the effect of misfit strain in the (ZnSe/FeSe) superlattices on the film quality.

The interface structure in a Ti/TiN multilayer material has been investigated by high resolution transmission electron microscopy (HRTEM). It was shown that the α-Ti and β-TiN layers consisted of many cylindrical crystals growing along the close packed directions normal to the surface of a stainless steel. There existed specific orientation relationship at the Ti/TiN interfaces without transition layers: (111)TiN ‖ (001)Ti, [110]TiN ‖ [100]Ti. However there was no such orientation relationship at the Ti/TiN interfaces with TixN (x >1) transition layers.

The electrical resistivity and crystal structure of three Ni-based periodic multilayer thin film systems (Al/Ni, Ti/Ni, and Cu/Ni) have been investigated. In each series of films the Ni layer thickness was systematically varied while the thickness of the ‘spacer’ layer (Al, Ti, or Cu) was fixed. In the Al/Ni and Ti/Ni systems films with very thin Ni layers (and consequently large volume fractions of spacer and ‘interfacial’ material) yielded very high resistivities which dropped rapidly with increasing Ni thickness. By contrast, the resistivity of Cu/Ni multilayers continuously increased with Ni layer thickness due to the decline in volume fraction of high conductivity Cu. Both the Al/Ni and Ti/Ni systems exhibit Ni(111) texture in the thicker Ni layer samples. As the Ni layer thickness decreases the Ni(111) peak loses intensity and broadens due to finer grain size and increasing disorder. Al-Ni and Ti-Ni compounds are also noted. In the Cu/Ni system, however, the sharpness of the Ni(111) peak passes through a minimum as the Ni layer thickness decreases but then increases for the thinnest Ni layer samples.

The growth and microstructural evolution of sputtered Ti/Ni and Ni/Ti bilayer thin films have been investigated as a function of Ti and Ni layer thicknesses in as-deposited and annealed states (280°C for 60 minutes) by transmission electron microscopy (TEM). The Ti layer thickness was varied systematically from 4.9 to 29.4 nm while the Ni thickness was varied from 3.2 to 19.2 nm. Carbon coated Cu TEM grids were used as substrates. Microstructural characteristics of the bilayers were found to be deposition sequence dependent. Ti/Ni bilayers exhibit a finer microstructure than N/T especially for the thicker films. Intergranular cracking is observed in the Ti/Ni sequence. In both deposition sequences the presence of Ni promotes the crystallization of Ti in the as-deposited state. By contrast, single layer Ti films deposited under the same sputtering conditions remain amorphous up to 9.8 nm thick. The Ti{002} electron diffraction ring is present in all of the bilayers even those with the thinnest Ti layers. Additional Ti rings, {010} and {011}, develop in bilayers with thicker Ti layers. In both bilayer systems a tensile stress parallel to the film plane is present in the Ni layer. Annealing removes structural defects and relieves the stress. A large increase in Ni{111} spacing can be attributed to dissolution of Ti atoms into the Ni lattice. Annealing also produces evidence of grain growth, intermetallic compound formation, and amorphization in both Ti/Ni and Ni/Ti samples.

Silicon-on-insulator structures were formed by the selective epitaxial growth (SEG) of silicon and the epitaxial lateral overgrowth (ELO) of oxide shapes using an LPCVD hot-walled reactor at 850°C. The homoepitaxial interface changed character with modifications of the gas composition during the in-situ pre-epitaxial bake at 900°C. HREM images show ellipsoid-shaped inclusions lying along the homoepitaxial interface for silicon growth conducted with no dichlorosilane (DCS) flow during the prebake in H2. SIMS analysis indicates a large oxygen, fluorine, and carbon concentration at the interface. For structures grown with a small DCS flow in addition to H2 during the prebake, the homoepitaxial structural defects and the oxygen, fluorine, and carbon peaks are removed.

Gate-quality SiO2/Si(100) interfaces were reproducibly fabricated using a two-step remote plasma-assisted oxidation/thin-film deposition processing sequence at temperatures between 200 and 300°C. The pre-deposition oxidation creates approximately 0.5nm of SiO2, and produces an SiO2/Si interface with a midgap trap density of ∼1.3×1010cm−2eV−1. The MOS capacitors prepared by this technique have properties comparable to those with thermal oxides grown at 850–1050°C. These capacitors also show a longer minority-carrier life time in the underlying Si than samples prepared using other pre-deposition treatment methods.

Nanocrystalline Nb100−xCux (0 ≤ x ≤ 30) alloys of 8 – 25 nm grain size are synthesized with the mechanical alloying technique. Differential scanning calorimetry reveals two separate stages of grain growth. In the first stage, the grain growth is associated with migration of solute Cu atoms to grain boundaries. Grain growth stops as the grain boundaries are saturated with Cu. The second reaction takes place either when the threshold for the nucleation of an Fcc Cu phase in the grain boundary is overcome by thermal activation, or when segregating Cu atoms in the grain boundary are driven by diffusion to the growing Cu grains, and the Cu concentration in the grain boundary drops. This increases the grain boundary energy, and initiates a second stage of rapid grain growth.

The thermal stability of electrodeposited nanocrystalline Ni-1.2%P and Ni-0.12%S alloys is evaluated by in-situ electron microscopy studies. Isothermal grain size versus annealing time curves at 573K and 623K show an unexpected thermal stabilization in form of a transition from rapid initial grain growth to negligible grain growth. This behaviour is discussed in terms of the various grain boundary drag mechanisms which may be operative in these alloys.

The present paper reports on the characterization and on sintering studies of nanometer-sized polycrystalline ZrO2 prepared by the technique of crystallite condensation, oxidation, and in-situ compaction. The annealing induced growth of crystallites as well as a transformation from the tetragonal to the monoclinic phase were observed. A rapid increase of the mass density and of the microhardness during annealing up to 1000 °C indicates attractive sintering characteristics. By means of positron lifetime spectroscopy the development of the pattern of structural free volumes during sintering was studied.

Binary mixtures of Fe-Cu powders in the range of 10–95 at.% Fe have been prepared by mechanical alloying and investigated by x-ray diffraction, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The final grain sizes of the powders vary between 6 and 20 nm, and depend on the composition of the material. Indications for the formation of single-phase alloys with up to 60 at.% Fe in Cu and 20 at.% Cu in Fe have been found although the Fe-Cu system exhibits only vanishingly small solid solubilities under equilibrium conditions. Between 60 at.% and 80 at.% Fe a two-phase region of fee and bec solid solutions exists. Alloy formation is discussed with respect to the thermodynamic conditions of the material. The influence of the large grain boundary fraction, as well as the role of internal strains and stored enthalpies introduced by ball milling, is critically assessed.

Nanocrystalline fee metals (Al, Cu, Ni, Pd, Rh, Ir) have been prepared by ball milling. The development of the microstructure is investigated by x-ray diffraction, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The final grain sizes range from 6 to 22 nm and scale with the melting point and the bulk modulus of the elements: metals with higher melting point and bulk modulus have a smaller final grain size. From this a general relation between the deformation mechanism during ball milling and the ultimate grain size achievable by this technique is inferred. With decreasing grain size the lattice strain is enhanced and deformation enthalpies of up to 40 % of the heat of fusion are stored in the material. The contributions of the lattice strain and of die excess enthalpy of the grain boundaries to the stored enthalpies are critically assessed. The kinetics of grain growth are investigated by mermal analysis. The activation energy for grain boundary migration is derived from a modified Kissinger analysis and estimates of the grain boundary enthalpy are given.

The effect of grain size on the corrosion behaviour of nickel in 2N sulphuric acid is evaluated by potentiodynamic testing and characterization of the corrosion morphology for grain sizes ranging from 100μ to 32nm. The influence of the grain boundary component on key electrochemical parameters (free corrosion potential, passivation current density and potential, transpassive dissolution rate) is discussed.

We have studied possible structural changes occur ing at the Sn/Ge interface of highly milled Sn/Ge composites. EXAFS and X-ray Diffraction measurements were made on mechanically milled powders having compositions ranging from 20 to SO vol.% Sn. X-ray diffraction measurements indicate the increasing amorphization of Sn as the Sn content is decreased. EXAFS results indicate that this amorphous phase is due to the formation of an a-Sn/Ge alloy. The EXAFS from this alloy did not change significantly at the Sn melting point. X-ray diffraction measurements made at room temperature show a systematic decrease in the intensity of Sn peaks and broadening of Ge peaks with the decreasing Sn content.

Recent work is reviewed on the structure of metal/metal oxide interfaces in model systems with well defined orientation relationships and boundary inclination. Structural relaxations established upon interface formation may be described as misfit dislocations which can be investigated using conventional and high resolution TEM. The conditions for obtaining informations at an atomistic scale using HRTEM are critically discussed. Specifically, geometrical restrictions are found to be critical in HRTEM study of {111} interfaces in fee metal -fee oxide systems. Different misfit dislocation networks at {100} interfaces in fee metal - fee oxide systems were observed which may be correlated to the relative strength of metal-anion and metal-cation bonds at the interface. In strongly interacting systems misfit dislocations can possess an equilibrium stand-off distance from the interface. In the system Nb-Al2O3 the interface is shown to be coherent by the registry of atomic columns adjacent to the interface. In this configuration energy is minimized by unbroken strong interfacial bonds and misfit localization in the elastically softer metal.

Metal-ceramic interfaces in theimodynamic equilibrium (Au/ZrO2) and non-equilibrium (Au/MgO) have been studied by TEM and HREM. In the Au/ZrO2 system, ZrO2 precipitates formed by internal oxidation of a 7%Zr-Au alloy show a cubic ZrO2 phase. It appears that formation of the cubic ZrO2 is facilitated by alignment with the Au matrix. Most of the ZrO2 precipitates have a perfect cube-on-cube orientation relationship with the Au matrix. The large number of interfacial steps observed in a short-time annealing experiment indicate that the precipitates are formed by the ledge growth mechanism. The lowest interfacial energy is indicated by the dominance of closed-packed {111} Au/ZrO2 interfaces. In the Au/MgO system, composite films with small MgO smoke particles embedded in a Au matrix were prepared by a thin film technique. HREM observations show that most of the Au/MgO interfaces have a strong tendency to maintain a dense lattice structure across the interfaces irrespective of whether the interfaces are incoherent or semi-coherent. This indicates that there may be a relatively strong bond between MgO and Au.

Interfaces in Cu/MgO, Pd/MgO, Pd/Al2O3, Ni/NiAl2O4 and Ni/Al2O3 systems produced by internal oxidation have been studied by transmission electron microscopy. For the Cu/MgO system, the MgO particles, with a cube-on-cube orientation with respect to Cu matrix, are faceted with principal faces parallel to {111} lattice planes of Cu and MgO. For the Pd/MgO system, the MgO particles, with a cube-on-cube orientation with Pd matrix, are faceted with interfaces parallel to the {100} and {111} lattice planes of MgO and Pd. Additional plate-like MgO particles with main facets parallel to {111} lattice planes possess a twin orientation relationship with the Pd matrix. Interfaces in Cu/MgO and Pd/MgO systems are all partially coherent with interfacial misfit dislocations. For the Pd/Al2O3 system, various transition oxide phases such as η, δ, and θ-Al2O3 and stable α-Al2O3 phase have been observed. The [1100] direction of α-Al2O3 is parallel to the [110] direction of Pd and the (0001) plane of α-Al2O3 is parallel or nearly parallel to the (110) plane of Pd. The NiAl2O4 spinel phase and Al2O3 phases are formed in Ni-Al alloys under two different oxidation conditions. The NiAl2O4 particles have a plate-like morphology with a cube-on-cube orientation relationship with the Ni matrix, while Al2O3 particles are randomly oriented.

The interfacial chemistry between Ni and Al2O3 has been studied during the initial stages of bonding. We have evaporated thin films of Ni on different alumina substrates (thin oxide film on metallic Al, polished and scratched sapphire crystals, surface with second phase precipitates) and have analyzed how the interface grows, in situ, using X-ray Photoelectron Spectroscopy. It was found that a certain fraction of the first monolayer of Ni which forms on the alumina surface undergoes charge transfer to form NiO. This is due to oxygen-active sites such as unattached oxygen bonds on the surface. A measure of the concentration of such sites can therefore be obtained from the submonolayer fraction of Ni that gets oxidized. It was found that a rough surface offered less oxidation sites for Ni than a smooth one whereas a surface with second phase MgAI2O4 (spinel) precipitates offered more oxidation sites. Also, there is much less oxidation on a thin film of amorphous alumina grown on metallic Al than on a polished bulk sapphire surface. The implications of these studies to further understanding of the metal-ceramic interface have been discussed.

The role of the ion species on the adhesion enhancement of ion beam mixed Fe/Al2O3 systems has been investigated. The ion implantations were carried out after film deposition using Cr (300 keV), Fe (320 keV), or Ni (340 keV) ions. The adhesion of the films was measured by a pull test and a scratch test. While the three types of implantation result in similar ion concentration profiles (with the peak concentration at the interface) and similar damage profiles, the three species were not equally effective in improving the adhesion. The effects are proposed to be due to changes in the interfacial energy resulting from both the damage and the presence of the ion species at the interface.