A void of cross sectional area A may spread perpendicular to the applied electric field Ea during electromigration because its leading surface develops a facet whose advance is limited by the supply of steps. If the facet is immobile (no step source) and the remaining surface is free to move, and if EaA is less than a threshold value, then the void assumes a stationary elongated shape dictated by a balance between capillarity and electric field. If EaA exceeds the threshold value, however, a balance is no longer possible, and the void spreads along the facet without arrest. If the facet has limited mobility, a balance is possible for all values of EaA, resulting in an elongated moving steady-state shape. The treatment simplifies the void shape as rectangular but preserves the essential features of capillarity and surface electromigration. We argue that the motion of a facet on a void along the outward normal requires defects (e.g. intersecting screw dislocations) that act as step sources since homogeneous nucleation of steps on the facet is expected to be negligible. Since voids in fine-line interconnects are often observed to be partially faceted, restricted void motion and resultant spreading which depend sensitively on crystallographic features, such as defect structure and grain orientation, may indeed limit the lifetime of fine-line interconnects in electronic devices.

Molecular-dynamics simulations were used to synthesize nanocrystalline silicon with a grain size of up to 75 Å by crystallization of randomly misoriented crystalline seeds from the melt. The structures of the highly-constrained interfaces in the nanocrystal were found to be essentially indistinguishable from those of high-energy bicrystalline grain boundaries (GBs) and similar to the structure of amorphous silicon. Despite disorder, these GBs exhibit predominantly four-coordinated (sp3-like) atoms and therefore have very few dangling bonds. By contrast, the majority of the atoms in high-energy bicrystalline GBs in diamond are three-coordinated (sp2-like). Despite the large fraction of three-coordinated GB carbon atoms, they are rather poorly connected amongst themselves, thus likely preventing any type of graphite-like electrical conduction through the GBs.

The atomic and the electronic structure of the Σ 5 (210) [001] tilt grain boundary in Ni3Al have been calculated using the full potential linearized-augmented plane-wave method. The strain field normal to the boundary plane and the excess grain boundary volume are calculated and compared with the results obtained using the embedded-atom method (EAM). The interlayer strain normal to the grain boundary oscillates with increasing distance from the grain boundary. The bonding charge distributions suggest that bonding in the boundary region is significantly different from that in the bulk. The grain boundary energy and the Griffith cohesive energy are calculated and compared with the EAM results.

We show that dramatically different in-plane crystallographic textures can be produced in body centered cubic (bcc) metal thin films deposited under different conditions. The orientation distribution of polycrystalline bcc thin films on amorphous substrates often has a strong (110) fiber texture, and an in-plane texture may develop when deposition takes place with an off-normal incidence flux of energetic ions or atoms. Three orientations in Nb films have been observed in which the energetic particle flux coincides with crystal channeling directions. In-plane orientations in Mo films have also been obtained in magnetron sputtering systems. The selected orientations are reviewed, and examples are given in which the in-plane orientation of Mo deposited in two similar magnetron sputtering systems differs by a 90° rotation. The origins of in-plane texture in rectangular magnetron sputtering systems are discussed.

The crystallite size and orientation in molybdenum films prepared by magnetron sputtering at a low rate of typical 1 Å/s and a pressure of 0.45 Pa was investigated by X-ray diffraction and texture analysis. The surface topography was studied using atomic force microscopy. Increasing the film thickness from 20 nm to 3 μm, the films show a turnover from a (110) fiber texture to a (211) mosaic-like texture. In the early state of growth (20 nm thickness) the development of dome-like structures on the surface is observed. The number of these structures increases with film thickness, whereas their size is weakly influenced. The effect of texture turnover is reduced by increasing the deposition rate by a factor of six, and it is absent for samples mounted above the center of the magnetron source. The effect of texture turnover is related to the bombardment of the films with high energetic argon neutrals resulting from backscattering at the target under oblique angle and causing resputtering. Due to the narrow angular distribution of the reflected argon, bombardment of the substrate plane is inhomogeneous and only significant for regions close to the erosion zone of the magnetron.

Zinc Oxide (ZnO) is one of the important Transparent Conducting Oxides (TCO) for thin film photovoltaic cells with respect to performance and cost reduction. When used in photovoltaic cells, the surface roughness of ZnO is required in order to increase the amount of light going inside the cells (Light Trapping). In this paper we present the surface morphology in connection with the fiber texture of ZnO films at different experimental conditions. The structural properties of the ZnO films grown by the method of radio frequency sputtering and Chemical Vapour Deposition (CVD) with the special effort to make surface roughness (Surface Texturing) are presented. The influence of the control over the fiber texture, surface mobility of the adatoms and the dissociation of water vapour during growth are explained.

The field of films and coatings is very broad. In general, the structure of films may comprise several phases, each having a different micro-structure and composition. These phases may be built up from grains which have different sizes, shape, morphology and orientation. A description of those types of films is complex and a large number of structural parameters is needed to fully characterize them. It is therefore more convenient to use a statistical description of them and to specify the relative proportion of different phases, grain orientation distribution [1], the orientation correlation between neighbouring crystals [2] and grain shape and size distribution [3]. Such a description provides details of the microstructural geometry of films, thereby giving a frame of reference within which various properties of films and a microstructural transformation of film structure, can be analyzed. Such microstructural descriptions have to be often supplemented by information about the nature and distribution of lattice defects, dislocations, stacking faults and antiphase boundaries. All this information put together, helps to provide a better understanding of the behaviour and various physical, chemical, mechanical and other properties, of films and coatings.

Thin Ag-Ni and Ag-Co layers with compositions of 0, 15, 22 to 28 at% Ni or Co were made by magnetron sputtering. TEM experiments revealed that the layers exhibited a {111} fiber texture with a high density of twins, always with the twinning plane parallel to the layer surface. X-ray diffraction and TEM results indicate that all Ni or Co is dissolved in the Ag, although some compositional inhomogeneity occurs: the layers are highly supersaturated with Ni or Co. Unlike the pure Ag layer, the Ag-Ni and Ag-Co layers exhibited high strains in the as prepared state.

Upon annealing Ni or Co precipitated. The Ni precipitates were small, spherical particles oriented parallel to the surrounding Ag. The strains in the Ag-Ni and Ag-Co layers after annealing were less than the calculated thermal strains, but they were larger than the strain in the pure Ag layer after an equal annealing treatment.

The growth surfaces of oxides formed at high temperatures on metallic substrates with different oxidation resistance were imaged using an atomic force microscope (AFM) in both contact and tapping modes. In addition to differences in morphology of NiO and TiO2 films, and their anisotropy of growth caused by the crystallographic orientation of substrate grains and by the type of substrate grain boundaries, some subtle growth features were documented. These include the nano-size steps of growth on the sidewalls of pyramidal grains of TiO2 and the nucleation at the intersection of NiO grain boundaries with NiO/gas interface. An example of a quantitative description of oxide/gas interface using roughness parameters is presented. This description is used to demonstrate the differences in evolution of oxide growth morphology for NiO doped with Ce growing by inward diffusion of oxygen anions or by outward diffusion of metal cations.

Crystalline quality and ferroelectric properties of (120)-oriented BaMgF^BMF) films grown on Pt(111)/SiO2/Si(100) and n-Si(111) substrates have been investigated. The BaMgF4 films grown on Pt(111) have large and flat grains, while the films on Si(111) have small grains. The C-V curve of BaMgF4/Pt(111)/SiO2/Si(100) diodes showed a hysteresis loop with a memory window of 3.8V.

Titanium oxide thin films were grown at different temperatures on (0001) α-Al2O3 substrates by molecular beam epitaxy (MBE). The films grown at room temperature were amorphous. Annealing at 1223K of 6 nm thick films led to the formation of TiO2 with an epitaxial orientation relationship (100)<001>TiO2 ∥ (0001)<01101>Al2O3 with the substrate. However, on similar heat treatment, thicker 100 nm films formed polycrystalline TiO2. At a deposition temperature of 1223K epitaxial Ti2O3 films with orientation relationship (0001)<2110>Ti2O3 ∥ (0001)<21101>Al2O3 were formed. The lattice mismatch between Ti2O3 and α-Al2O3 was accomodated by a regular arrangement of misfit dislocations at the Ti2O3/α-Al2O3 interface. By comparing the microstructural evolution of the annealed films with that of those films grown at high temperature, mechanisms governing grain growth in polycrystalline titanium oxide films were discussed.

Nanocrystalline SnO2 thin films, prepared by electron beam evaporation from high purity SnO2 and post deposition annealing in air at 700°C with different times, were investigated using HRTEM. The films are composed of nanocrystalline SnO2 crystallites and pores. Many of the crystallites consist of crystal defects, such as crystallographic shearing planes (CSPs), dislocations and twin boundaries (TBs). Atomistic structures of these defects were investigated. These defects interact with each other, resulting in different configurations of crystallites. The local composition at CSP and TB steps at dislocation cores varies with the type of dislocations and CSPs and is different from the stoichiometric composition of SnO2. Thus, the electronic structure at these defects is different from that of the perfect SnO2.

A polycrystalline diamond film was grown on the polished surface of silicon substrate in H2-CO-O2 mixing gas. Atomic and electron structure of grain boundaries in the film was investigated by both high resolution electron microscopy and electron energy loss spectroscopy. CSL boundaries in the film showed characteristic feature in atomic structure; Σ 9 CSL boundary was parallel not to (221) plane but to (114) plane. A new line which correspond to π * state was found in addition to major σ * line in the EELS spectra of the boundary which contained three coordinate atoms. Observed π * line shows occurred change of a dangling bond (pz electron) to π state. No π * line appeared in the EELS spectra obtained from boundaries which contained no three coordinate atom such as (111) Σ 3 boundary.

The grain boundary misorientation distribution of 203 grain boundaries in bulk processed high Tc superconductor YBa2Cu3O7-δ with five processing conditions, was studied. Two complementary analytical approaches, Grain Boundary Misorientation Distribution (GBMD) from the random description, using a hypothesis test and X2 analysis, and Grain Boundary Character Distribution (GBCD), using the Coincidence Site Lattice (CSL) model, were applied. The GBMD and GBCD both showed grain boundary evolution departing from a random distribution above 935°C processing temperature. The GBCD analyses indicated an approximately linear increase in the population of CSL-related boundaries, among which the tetragonal CSL (c/a ≠ 3) boundaries grew in the same trend while orthorombic boundaries (c/a = 3) became stagnated. The results from comparing the corresponding GBCD and volume averaged Jc for each batch indicated that the tetragonal CSL boundaries were oxygen deficient and accounted for, among other current limiting factors, lower current carrying ability.

Analysis is described to extract the excess free energy of grain boundaries from the mesotexture of well-equilibrated polycrystalline samples. The approach is based upon the force and torque balances at triple junctions described in the classical work of Herring [1]. The main advantage of the approach is that the free energy function is obtained over the full fundamental zone of grain boundary types. For the purposes of exposition, the method is described for specified two-parameter hypersurfaces in the fundamental zone for cubic polycrystals (the sets of pure <100> and <111> tilt boundaries) and the free energy is assumed to depend only upon the lattice misorientation. Results from testbed simulations are presented.

When a grain boundary is terminated by a free surface, its behavior may be significantly different than for the same boundary either in an infinite bicrystal, or terminated by triple junctions. In this paper we describe some phenomena related to the free-surface interactions of interfacial dislocations, in thin films. We show that surface relaxation stresses can exert a powerful destabilizing influence upon the dislocation structure of many grain boundaries, and that they can only be made stable if a large lattice friction stress, or other pinning force, resists the motion of the dislocations. Finally, we will show that the only intrinsically stable grain boundary in a thin film is a tilt boundary with its rotation axis parallel to the normal of the film.

An attempt was made to apply the statistical analysis of NiO grain boundaries to explain the dependence of NiO growth kinetics on the crystallographic orientation of Ni substrate. Study was conducted for two crystals faces of Ni, (100) and (111), which exhibits a difference in oxidation rate constants at 1073 K, over one order of magnitude. The orientation distribution functions (ODF), calculated from X-ray measurements for NiO grown on both Ni faces, were analyzed numerically to assess the grain boundary character. The grain boundary misorientation distribution (GBMD) and grain boundary character distribution (GBCD), used to describe oxide structure, were derived using three different assumptions regarding the spatial correlation in orientation of neighbouring grains. Grain boundary network was created to analyze the high temperature diffusion properties through the oxide using diffusion constants available in the literature under assumption of various contribution of bulk and grain boundary diffusion paths to overall transport of ionic species. The growth parameters obtained were finally verified by comparison with experimentally measured oxidation kinetics.

A one-nanometer scale transmission electron microscope electron probe X-ray microanalysis characterization of as-deposited and annealed aluminum - 11.5 at.% zirconium multilayer samples in cross-section synthesized by magnetron sputtering is reported on here. Composition line profiles were acquired across Zr layers in as-deposited material and samples isochronnally annealed in a differential scanning calorimeter to temperatures of 290°C and 485°C. A spatial resolution of approximaty 1.5 to 2.0 nm was achieved in these experiments and will be improved by deconvoluti on of the instrumental electron probe function from the data. The as-deposited structure consisted of crystalline Al and Zr layers with thin amorphous layers at the Al/Zr interfaces. The amorphous interface layers increased in thickness upon annealing to 290°C. Additionally, at 290”C a metastable cubic alloy forms at the Zr deposited on Al interface. Upon heating to 485°C a multilayer of Al and metastable cubic AlxZr1-x phase is formed. The electron microscopic experimental technique, observations and data analysis will be discussed as applied to these multilayered materials.

CdSe appears to be a promising material to replace amorphous hydrogenated silicon as the photosensitive part in the retina of the “Electronic Eye”, a camera based on thin film technique. We have investigated the influence of post-depositional annealing treatments with respect to the optimization of the photoconductive properties. TEM-, AFM- and XPS-measurements on CdSe thin films are reported. The formation of an oxide could not be detected by XPS-depth profiling of films annealed in air but chemisorption of oxygen is expected at the intergrain boundaries. Hence, high potential barriers for electron transport will be introduced. Under illumination, trapping of photo-generated holes will neutralize the charge at the intergrain boundaries leading to improved electric properties. However, the homogeneity of the photoconductive properties in CdSe is not yet satisfying. The formation of swellings and holes on the sample surface, found by AFM-measurements, can perhaps explain the inhomogeneity of the photoconductive properties. Using Si wafers as substrate material no improvement in texturing could be reached, since an amorphous CdSe-interlayer is formed.

Ti thin films were grown by molecular-beam epitaxy (MBE) on α-Al2O3(0001) substrates. During room temperature deposition, in the very initial growth stage, AES investigations revealed a chemical reaction between the Ti and the α-Al2O3 substrate. An analysis of the AES data based on simple assumptions showed that ∼ 2 monolayers of Ti are oxidized. However, HRTEM analysis indicated an atomically smooth, incoherent interface, without a reaction layer. Reflection high-energy electron diffraction (RHEED) analysis revealed an epitaxial orientation relationship (0001)<2110> Ti ∥ (0001)<1010>Al2O3 between Ti and α-Al2O3(0001).