A lot of efforts have been devoted to understanding an interfacial structure. But, there are some difficulties about it as follows: An interfacial structure depends on a surface structure of a substrate and its temperature. Also, an interfacial structure is not homogeneous in general because of a lattice mismatch between a substrate and an overlayer thin film.

Ultrahigh vacuum transmission electron microscope (UHV-TEM) is very powerful to observe clean surface and the fabrication during deposition on the surface. Since structural information can be obtained from 10 nm-sized area to a few μm area using TEM, UHVTEM is very appropriate to investigate interfacial structure in detail.

In this study, structure of Ag/Si(111)--R30-Ag interface was observed by UHVTEM. Especially, it is interesting whether the superstructure is conserved at this interface or not. The Si(l11)- as the substrate surface was obtained by Ag 1ML deposition on Si(l11) 7×7 surface at 673 K.

Multilayer film (MLF) structures which exhibit giant-magnetoresistance (GMR) properties have applications in the areas of magnetic recording and computer memory. The magnetic properties of MLF structures are dependent upon structural and compositional variations at the atomic level. Thus, structural characterization with high spatial resolution, especially at layer interfaces, is important in order to optimize device performance with respect to processing and operating conditions. Atom probe field ion microscopy (APFIM) is one technique that has the capability to characterize the local structure and composition of MLF devices with sufficiently high resolution. However, a major difficulty has been successful specimen preparation from MLF materials, which requires fabrication of a sharply pointed needle (radius <50 nm) containing the layers of interest in the apex region. Research on specialized field ion specimen preparation techniques which use focused ion beam milling has recently enabled nanoscale MLF structures to be investigated. In the present paper, the application of atom probe microanalysis to two different MLF structures is presented.

One-, two- and three-layer polytypes are common in muscovite (sheet silicate). Based on high-resolution transmission electron microscopy (HRTEM) and analytical electron microscopy (AEM) examinations, we report in the discovery of complex 5-layer and 7- layer polytypes in natural muscovite for the first time (Fig. 1) and the implications of polytype transitions.

Three main structures are found in muscovite crystals in a sample from Oreana, Nevada, which are 1M, 2M1, and a disordered structure often containing short-range ordered stacking sequences. On the scale of a few micrometers, muscovite occurs as ordered crystals, disordered crystals, and crystals with regions of ordered and disordered layer stacking.

Short-range ordered 5- or 7-layer repeats are found in some disordered structures where single 4-, 6-, 9- or 10-layer intergrowths occur occasionally with 2- and 3-layer repeats. Such complex polytypes have not been observed before in either natural or synthetic muscovite, although 5- and 7-layer structures are commonly present in trioctahedral micas (i.e., biotite) (Baronnet, 1992).

SrTiO3-based semiconducting ceramics are widely used to electric devices such as dielectric condensers and varistors due to their properties of high dielectric constant, high dispersion frequency and small temperature dependence of the dielectric constant. The electric properties of these ceramic devices have been studied and found to be deeply influenced by the crystal growth mechanism, the grain boundary layer characteristics and the sintering atmosphere that is represented by such factors as oxygen partial pressure and processing temperature which relate to the atom vacancy formation. Atom vacancies, which play an important role to the electrical properties, have been detected by cathodoluminescence (CL) spectroscopy with scanning electron microscopy (SEM).

A ceramic condenser (Sr0.94Ca0.05Ba0.01)0.99TiO3 was investigated by Hitomi el at: using transmission electron microscopy (TEM). The material is a boundary layer (BL) semiconducting ceramic condenser, having dielectric layers between semiconducting grains. The same condenser material was investigated in this report at the grain boundary region using high resolution (scanning) transmission electron microscope (TEMSTEM) capable of High Angle Annular Dark Field (HAADF) technique.

Grain boundaries have long been known to have a deleterious effect on the superconducting critical current that can be carried by YBa2Cu3O7-δ. Recent theoretical analyses have proposed that the origin of this behavior may be band bending, which results in the depletion of charge carriers at the grain boundaries. For this to occur in these p-type superconductors there must, by definition, be a high density of localized donor states in the boundary plane. Here we describe a structural feature intrinsic to all [001] tilt boundaries that may be the origin of these localized states.

Direct atomic-resolution images of asymmetric [001] tilt grain boundary structures have been obtained using the Z-contrast imaging technique. The grain boundaries are observed to be composed of distinct structural units, as shown in figure 1. Within these structural units, a 2×1 reconstruction of the CuO columns is seen to occur. This reconstruction, which is caused by the constraint imposed on the structure by the sizes of the component atoms, leads to effective oxygen vacancies in the grain boundary plane (figure 2). Further oxygen annealing of the boundary cannot fill these vacancies as there is no space in the structure for more oxygen atoms.

In the last decade, Pd-Ge contact system emerged as the most promising replacement of the Au-Ni-Ge alloy, still used by most of today's GaAs technology. Its better electrical properties stem from the fact that contact formation is based on a series of solid state reactions without any melting of the metal thin films and the GaAs substrate taking place during annealing. Research studies by E.D. Marshall et al. (1) demonstrated that thermally stable contacts with low resistivities could be achieved by low temperature annealing of Pd and Ge thin films. Their studies also revealed that the excess Ge is regrown on top of the GaAs substrate by a solid state epitaxy mechanism.

Typical TEM cross-sectional specimen preparation techniques limit the electron transparent area and make the global characterization of the contact difficult. In this study, we employed a focus ion beam (FEB) method as described by Bassile et al.(2), which allowed us to observe a minimum of 4 microns of the interface cross section in each of the specimens examined.

Aluminum-magnesium alloys are currently being utilized in lightweight automotive components and their good strength and weldability characteristics has made them candidates for increased use. The primary problem with using aluminum alloys for automotive applications is their relatively low formability. Superplastic forming (SPF) is a viable method for producing high elongations and is enabled in these alloys by the manipulation of intermetallic particles (e.g. Al3Sc) that restrict grain growth at the high homologous temperatures necessary for this technique [1]. SPF of Al-Mg-Mn-Sc alloy has yielded elongations of over 600% [2]. However, Al3Sc particles age rapidly at high temperatures which can reduce their strengthening characteristics following deformation. It has been experimentally observed that the addition of Zr to Al-Sc alloys retards the aging of the Al3Sc precipitates [3]. This is beneficial for high temperature conditions like superplastic forming and welding. In this study we examine the location of Zr in the strupturc and how it may be inhibiting particle aging.

A comprehensive understanding of the relation between structure and properties in nano-materials calls for an extensive knowledge of the adhesion between nanoparticles. Electron diffraction contrast from the stress field caused by adhesion between contacting particles yields a detailed information on surface energy, grain boundary energy, dislocation and interphase formation mechanisms. However, the image interpretation is hindered by the scarcity of defined image condition data to fit the theoretical simulations due to the non-trivial TEM experimental situation on such a nanometric scale.

In our contribution, we challenge the above characterization complications by initiating CBED, HREM, and EELS on contacting nanoparticles with a CM200 FEG TEM. The main objective of our investigation is a quantitative simulation of the contacting stress field images from contacting nanoparticles and a quantitative characterization of the adhesion properties. In our approach, we started with cobalt particles which were coherently precipitated in a Cu-Co0.2wt% alloy, and then extracted using the carbon evaporation replica technique.

Bilayer thin films have been utilized in superconducting transition-edge sensors (TES) for photodetector development. A TES is formed with a normal metal conductor film and a superconductor film, so called bilayer, deposited on a subtract. In its,transition temperature region, the resistance of the superconductor film is extremely sensitive to the temperature. When an incident radiation ray arrives, the temperature of the bilayer increases, leading the resistance increases tremendously. A superconducting quantum interference device measures the current variation for read-out. By varying the relative thickness of the normal metal conductor layer and the superconductor layer, one can adjust the transition temperature of the bilayer to a desired range according to the proximity effect. TES bilayers are fabricated on Si-based substrates for the development of infrared, ultra-violet, and x-ray detectors.

Various normal and superconducting metal combinations are considered as bilayer candidates. When two metals are brought together, the concerns usually rise to those materials issues that may affect TES performance.

Chromium films are commonly used as a metal “glue” layer because of good adhesion to glass. It is believed that an intermediate oxide layer is formed during deposition, since Cr has a very strong affinity for oxygen. For example, a graded Cu/Cr/CrOx/SiO2 structure ensures excellent adhesion of Cu to glass, whereas Cu exhibits poor adhesion to most dielectrics. In our recent study, however, a diffusion layer, Cr2O3+SiOy, was observed between CrOx and SiO2 (glass) substrate. It is quite likely that this diffusion layer is responsible for the good adhesion of Cr film to glass.

The relative compositions of the major components across the interface are shown in Fig 1. A Cr film was evaporated on Corning Code 1737 glass (Al2O3-B2O3-SiO2 with ˜67at.% Si02) substrate at room temperature (RT) and subsequently covered with about lOnm Cu. A 5nm'wide diffusion layer is seen. The corresponding regions are also indicated in Fig 2, an Annular Dark Field (ADF) image whose contrast is approximately proportional to the density if the thickness is assumed uniform.

The TEM thickness fringe method [1] was developed as a potential routine technique to determine compositional profiles in quantum well systems. This technique has the advantages that a) TEM sample preparation is simple and the experiment is easy to set up and b) thickness fringe profiles show fine structure which is sensitive to chemistry [2]. In this paper, we demonstrate the ability of the method to measure the chemical abruptness at the interface between two layers of different composition.

90° wedge AlGaAs/GaAs TEM samples were prepared by the cleavage method, where the samples were cleaved along two orthogonal {110} planes. The samples were mounted on Cu grids and were investigated in a Philips EM430 TEM. Samples were orientated to the [100] direction precisely and bright-field images were acquired digitally using a CCD camera. Fig 1 shows an enlarged image of thickness fringes.

Since the edges of samples are 90° wedges, the thickness at any point can be accurately determined and the fringe profile can be compared with fringe profiles calculated for a range of Al compositions.

Owing to its unique and outstanding physical-chemical properties, diamond is considered to be one of the most important potential materials for applications such as in mechanical, optical, thermal, and electronic devices. Among them, the most attractive application of diamond would be a semiconductor for high temperature and high power electronic devices. To realize such novel devices, a high quality of defect-free single-crystal diamond film is required. Recently, continuous diamond films are found to be able to grow on Pt(lll) substrate. Since the diamond film synthesized on Pt shows a high degree of epitaxy, this approach has drawn the attention of reseafchers in this field and some research results have been reported. However, the heteroepitaxial mechanism is still to be elucidated; in particular, why does diamond grow heteroepitaxially on the Pt substrate and how do the atoms align in the interface between diamond and the Pt substrate? In order to solve those problems, it is very necessary to study the diamond growth mechanism on an atomic scale.

Grain boundaries and related planar defects in crystalline materials are often characterized by relaxations from geometric lattice constructions in order to lower the interfacial energy. Grain boundaries may relax by local reconstructions of the atomic structure along the interface and/or rigid-body lattice translations that perturb the relative positions of the grains far from the interface. Rigid-body lattice translations can by studied using α-fringe contrast along planar interfaces in strong-beam transmission electron microscopy (TEM) images.[l-3] Oscillatory fringe contrast may appear along an interface between two grains which are related by a translation vector, R, when the interface lies inclined to the incident electron beam and imaged with a diffraction vector, gc, common to both grains.[4] The fringe contrast is due to an interference between the direct and scattered electron beams when the diffracted electron beams undergo a phase shift propagating across the interface. The phase shift, α, is proportional to the projection of R onto gc (i.e. α = Rgc) and the fringe contrast is known as α-fringe.

Quantum confinement effects in opto-electronic materials have typically been limited to onedimensional confinement due to the constraints of epitaxial growth techniques. One method of forming higher degrees of confinement is the spontaneous lateral modulation seen in InAlAs shortperiod superlattices (SPS) grown on InP(00l). Here, a small number of monolayers (0.5 ˜ 2) of InAs and AlAs is alternately deposited by MBE to build a layer that exhibits lateral modulation on the 10 ˜ 25 nm scale. These materials show strong polarization and a large red shift (˜500meV) of the photo-emission spectra.

A key to understanding and predicting the properties of these films is determining their composition distribution. Using an HB-501 STEM, we have investigated the detailed composition distribution within a strongly modulated sample. The sample was grown in slight tension with respect to the InP substrate, a condition in which lateral modulation is known to be strong. Figure 1 shows a highangle annular dark-field (HAADF) image together with an intensity line scan from the image.

In the copper metallization adopted for better speed and reliability in microelectronic devices, the choice of underlayer is one of the major concerns. Its requirements include low electrical resistance, adhesion to Cu and adjacent dielectric materials, confinement of Cu from drifting, and nucleation and texture enhancement of the overlying Cu film. Metallic tantalum is a very promising candidate. In this paper, the thermal stability of Cu/Ta interfaces is investigated to estimate the reliability of such a Ta underlayer.

Thin Cu and Ta films were consecutively deposited without breaking vacuum using a dc sputtering method to simulate the seed layer and underlayer in a Cu metallization structure. All the synthesized Ta films were the metastable tetragonal structure rather than the stable body-centered cubic (bcc) phase.

We have shown that (111) Cu grows epitaxially on top of (002) tetragonal Ta even though the Cu and Ta have hexagonal and tetragonal atomic arrangement on those planes, respectively. Using electron diffraction in cross-sectional and plan-view samples, an unexpected atomic matching at the interface was discovered as shown in Figure 1(b).

Quantitative evaluation of coherency strains in Ni-12 at.% Al alloys has been performed by means of high resolution electron microscopy (HREM) and convergent beam electron diffraction (CBED) techniques. The alloy Ni-12 at.%Al is composed of two phases, the disordered fee Ni-Al solid solution and the coherent Ni3Al (γ') particles with an LI2 structure. The presence of γ' particles can impart excellent mechanical properties to these alloys. However these particles coarsen if subject to high temperature with an important reduction of mechanical properties. Coarsening of coherent particles in solid alloys is driven by the decrease of surface and elastic energies. The effect of surface energy is well understood but that of the elastic energy still requires experimental investigation. The source of elastic interaction between particles is the lattice parameter mismatch between particles and matrix. Evaluation of the elastic strain fields around particles can give some insight into the elastic interaction between particles and thus into the coarsening mechanism from an experimental viewpoint.

The mechanical properties of Al-Cu-Mg alloys depend on a dispersion of Al2CuMg phase precipitates which form as laths along <100>A1, with {012}A1 as the habit plane. Despite extensive study, the crystal structure, morphology and interface structure between the Al2CuMg intermetallic phase and the Al matrix are still not well understood. Since the mechanical behavior of Al alloys strengthened by the S-phase cannot be controlled without a clear understanding of its crystallography and interface structure, the goal of this investigation was to characterize the crystal structure, evolution and interface structure of the S-phase using quantitative electron beam characterization techniques. Several models have been proposed for the crystal structure of Al2CuMg. A widely accepted model of the S-phase was given by Perlitz and Westgren (PW) [1], shown in Fig. 1. The unit cell of the PW model is orthorhombic with unit cell dimensions a = 0.4 nm, b = 0.923 nm, and c = 0.714 nm, space group Cmcm, containing 16 atoms in the ratio Al:Cu:Mg = 2:1:1.

It is well documented that the pulsed laser vaporization of graphite produces both carbon nanotubes and C60 in the presence of certain metallic catalysts. In nanotube production most of the Ceo is removed along with other residual contaminants during succeeding purification and annealing steps. The possibility of C60 becoming trapped inside a nanotube during this elaborate sequence has been considered but not previously detected.

Nanotubes are observed with high resolution transmission electron microscopy under conditions chosen to minimize both exposure time and irradiation damage. Since a nanotube satisfies the weak phase object approximation, its image is a projection of the specimen -potential in the direction of the electron beam. The image has maximum contrast where the beam encounters the most carbon atoms, which occurs where it is tangent to the tube’s walls. Thus, the image consists of two dark parallel lines whose separation is equal to the tube diameter, 1.4 nm.

The noble metal (Me = Au, Pd, Rh, and Pt) polynuclear coordination compounds of Chini’s type eventually serve as a remarkable bridge between molecular clusters and metal colloids. The sizes of the metal cores of the cluster compounds are close to lower sizes of colloidal metal particles. However, chemically stabilized nanoclusters have a distinct ligand environment with a definite stoichiometry inherent to molecular clusters. Interest in structures of the cluster compounds has increased in recent years in view of their unique selective catalytic properties under mild conditions, which, in principle, open a way to the development of a new branch of catalysis by metal clusters, quantum-size effects in the thermodynamic properties, and applications as nano-sized electronic devices (quantum dots). A key feature in structural characterization of such species (they are amorphous solids usually unsuitable for x-ray diffraction analysis) is to understand the relations between the atomic arrangement, electronic structure and chemical reactivity.

Three-dimensional structure studies provide important information about the organization of macromolecules, often revealing biological mechanisms and protein structure-function relationships. 400 KV electron cryo-microscopy is an emerging technology that is proving to be a powerful tool for studying the structures of large macromolecular assemblies that are often not tractable using other techniques. Its large depth of field makes it well-suited for imaging large objects to high resolution. In addition, a high accelerating voltage minimizes chromatic aberration yielding images of higher contrast. Recently a 400 KV electron cryo-microscope has been used to image periodic arrays of tubulin to 3.5 Å and single particles at somewhat lower resolutions (13 Å) providing practical demonstrations of its usefulness in modern structural biology. In this paper we present high resolution image data of two large icosahedral viruses: herpes simplex virus IB nucleocapsid (HSV IB) and rice dwarf virus (RDV). Human herpes virus (HSV) is associated with a spectrum of diseases ranging from cold sores to more severe clinical manifestations such as mental retardation.