Scanning microscopy is the only technique available for directly imaging the short-range structural features of the crystalline-to-amorphous (C-A) transition. Cleaved sheets of muscovite were implanted with 600 keV argon ions in order to induce radiation damage; thus producing the C-A transition. AFM images of Ar-implanted muscovite show the surface structural features of the C-A transition. Low-resolution images show a progressive increase in the surface roughness of muscovite with increasing ion dose, as seen by the development of hummocky microtopography, whose individual hummocks are 25 nm across. High-resolution AFM images of unimplanted muscovite reveal a highly crystalline structure, as shown by the hexagonal arrangement of the (SiO4)-tetrahedral layers. By scraping through the uppermost surface layer of the implanted samples, using a cantilever forces of 50 - 100 nN, the C-A transition is recognized by a decrease in the long-range order of the tetrahedral layers. Accordingly, crystal defects and highly disordered regions increase in frequency and size with Ar-dose. At the highest Ardose, disordered regions dominate the structure, lending complications to AFM image interpretation. Surface hardness decreases with higher radiation doses, as evidenced by the greater ease of scraping through atomic layers in the more damaged samples.

A water-soluble protein, ferritin, on a silicon surface has been imaged in pure water at room temperature with the atomic force microscope (AFM). The samples were prepared by binding ferritin molecules electrostatically to a charged polypeptide layer of poly-l-benzyl-L-histidine (PBLH). The hexagonal arrangement of ferritin molecules was imaged with high reproducibility, since the force between tip and the sample surface could be kept sufficiently lower than 10-10 N. The applied force can be stabilized and weakened mainly due to a “self-screening effect” of the surface charges of the ferritin-PBLH layer. We demonstrate that the electrostatic-binding sample preparation is one of the suitable methods for soft biological specimens to achieve the nondestructive. low-force AFM imagings.

Artifacts dominate atomic force microscope (AFM) images of nanoporous and mesoporous inorganic oxide materials taken under ambient atmospheric conditions with currently available tips. Artifacts in these AFM images are attributed to tip-sample interactions and the sharpness of tips on currently available cantilevers. We show that by modifying currently available AFM tips with carbonaceous materials, many image artifacts are eliminated. To characterize image artifacts, a variety of fiducial samples with feature sizes between ∼100 Å and 2,000 Å are used. One of the most useful fiducial samples is a close packed array of holes in a commercially available alumina membrane and we suggest that it be adopted as a standard fiducial sample.

The atomic arrangements of the α-7×7 phase and incommensurate phases of Al adsorbed Si(111) surface are investigated respectively by scanning tunneling microscopy (STM). STM images of α-7×7 surface reveal that characteristic triangular structures consisting of three Al adatoms situated on the center part of each half unit cell. The three Al adatoms form a triangular cluster and are bonded to the center adatoms. In this situation, the dangling bond of the center adatom is saturated, which would modify its electronic structure into non-metallic. The incommensurate phase is consists of approximately 9×9 structures, which are separated each other with misfit dislocations. In the “9×9” structure, individual Al atom is visible arranged in threefold symmetry.

Grain boundaries in quenched and aged Cu-i.5%Sb were examined with Auger electron microscopy, transmission electron microscopy, and high resolution electron microscopy. The ∑=3 grain boundaries are strongly faceted, with the facets lying primarily along the coincident (111) planes of the two grains. The grain boundaries are enriched in antimony, as demonstrated by both AES and HREM. HREM images of the ∑=3 (111) ║ (111) grain boundary differ from those of the Cu-Bi ∑ =3 (111) ║ (111) grain boundary in the lack of a significant grain boundary expansion to accommodate the excess solute at the boundary. A preliminary investigation of the atomic structure of the ∑=3 (111) ║ (111) facet by HREM and multislice calculations is presented.

High resolution imaging technique is applied to systematically study the ∑ =3 NiSi2(111)/(115)Si and NiSi2(221)/(001)Si interfaces. The long-period boundaries of ∑ =3 NiSi2 (111)/(115)Si and NiSi2(221)/(001)Si have been shown to decompose into short period of symmetrical NiSi2 (111)/(111)Si and NiSi2 (112)/(112)Si atomic facets which are similar to the case of asymmetrical twin boundaries in NiSi2 crystal. This result is consistent with the computer simulation in grain boundary case that asymmetrical tilt boundaries which are generally of longer periods may facet on an atomic scale into short period symmetrical boundaries.

The domain-related atomic faceting interfaces have been found in both of.∑ =3 NiSi2(111)/(115)Si and NiSi2(221)/(001)Si interfaces. The coexistence of two domain-related atomic faceting interfaces in the ∑ =3 NiSi2(111)/(115)Si has also been observed in different area of an interface which are separated by a 1/4<111> type of dislocation associated with a ‘demi-step’. The Burgers vector and step of a dislocation required to separate two domain structures in the ∑ =3 NiSi2/Si interface can be derived from the CCSL model.

General high-angle tilt grain boundaries may be described by an arrangement of repeating structural units. Some grain-boundary defects may also be modeled by the incorporation of structural units of related boundary structures into the boundary. The simulation of these structures requires the use of prohibitively large unit cells. The possibility of modeling these boundaries by the superposition of image simulations of the individual structural units isinvestigated.

The surface structure of “pure” oxides as well as the same materials after promotion by alkali metals, models of the oxide surface based on results of image simulation procedure have been proposed. The surface structure reconstruction of the catalysts upon electron beam irradiation was also observed. For the specimens under investigation surface steps and kinks were shown to be essential for strong interaction between oxides and supported Pt particles preventing their migration and suppressing the sintering process.

Interfaces in Reaction Bonded Silicon Carbide (RBSC) have been characterized by Analytical and High Resolution Electron Microscopy. Both Si/SiC and SiC/SiC interfaces were free of any oxygen impurity segregation, but contained metallic impurity precipitates. Oxygen was detected in the second phase particles in the SiC grains. A model is presented to explain the evolution of these second phase particles in the SiC grains.

An electron microscopy investigation has been conducted in ZnO:Pr:Co varistor structures prepared by a new in-diffusion method. It has been shown that some boundaries host intergranular precipitates of a Prx Oy-based phase. All observations lead to the conclusion that grain boundaries exhibit Pr segregation, while Co is homogeneously distributed in the ZnO matrix. No continuous intermediate layer is present at the ZnO/ZnO boundary nor at the Pr2O3/ZnO interfaces. This is consistent with a barrier model based solely on a space charge depletion region(s).

The interlocking of Nb1+αS2 platelets developed during sulfidation of Nb results in formation of a compact scale. The atomic structure and defects of these platelets were investigated using HREM. The resulting microstructure is very different from conventional microstructure consisting of polygonal grains and polyhedral grain boundaries because of the anisotropy of the crystal structure. The principal phase was identified as 3R-Nb2+αS2 intergrown with 2H-Nb1+αS2, or with some other arrangement of S-Nb-S slabs. The -S6- octahedral sites between two S-Nb-S slabs provide accommodation for extra Nb or foreign atoms and the large non-stoichiometry of Nb1+αS2. Stacking faults along the c axis account for the high density of planar defect structures observed within almost every platelet. Axial lattice fringe images and streaking in the diffraction pattern indicate that the planar defects are normal to the c direction.

A nondestructive three-dimensional RBS/channeling analysis system with an atomic resolution has been designed and is being constructed in Osaka University for analysis of nanostructured surfaces and interfaces. An ultra high-vacuum sample-chamber with a threeaxis goniometer and a toroidal electrostatic analyzer for medium energy ion scattering (MEIS) was combined with a short acceleration column for a focused ion beam. A liquid metal ion source (LMIS) for light metal ions such as Li+ or Be+ was mounted on the short column.

A minimum beam spot-size of about 10 nm with a current of 10 pA is estimated by optical property calculation for 200 keV Li+ LMIS. An energy resolution of 4 × 10-3 (AE/E) for the toroidal analyzer gives rise to atomic resolution in RBS spectra for Si and GaAs. This system seems feasible for atomic level analysis of localized crystalline/disorder structures and surfaces.

We report on new experimental studies of the Ge(111)-c(2×8) reconstruction performed with low-energy electron diffraction. (LEED) and scanning tunneling microscopy (STM). Weak quarter-order reflections are present in the c(2 × 8) LEED pattern in agreement with previous observations and results of ab initio calculations. In order to gain insight into the predicted splitting of dangling bond states, we compare constant current topographs (CCT's) performed at high-tunneling currents (40.nA) with first-principles calculations of the local density of states (LDOS) 1Å above the surface adatoms and obtain good qualitative agreement. We finally discuss to what extent the STM CCT's at high tunneling currents (small sample-tip distances (STD)) are sensitive to surface states outside the Г point.

The experimental apparatus and its optimization for holographic imaging with energy dependent photoelectron diffraction are described. A substantial improvement in data taking efficiency has resulted, allowing total data collection time to be reduced to about twelve hours for a single image-map.

For GaAs (001) and (III) we have measured the photoelectron diffraction patterns at a kinetic energy of 86 eV. We applied an extended Fourier-transform algorithm to the (001) data to obtain real space images. The origin of structures in these images not representing atomic positions is investigated with the help of single scattering calculations

Angle-resolved electron intensity distributions for Auger and photo- electrons are calculated using a curved-wave electron scattering formalism and compared with experiment. The distributions are found to depend significantly on both the ℓ and mℓ quantum numbers of the scattered electron. We consider the simple metals Ir and Al. Although the intensity patterns depend strongly on the ℓ quantum number at relatively low energy, even at high energies (around 1500 eV), a significant ℓ effect remains, which we find arises from nearest neighbor single scattering and from the multiple scattering or defocussing effect. The relative contribution of each ℓ and mℓ partial wave is determined not only by the quantum mechanicaf matrix elements, but also by the energy, polarization, and direction of the excitation beam.

Studies in ballistic-electron-emission spectroscopy (BEES) have enabled precise energy measurements of Schottky barrier heights with excellent spatial resolution and, more recently, it was shown that even scattering at the metal/semiconductor interface affects the BEES spectrum [1]. Monte Carlo simulations have been done to predict the spatial resolution of ballistic-electron-emission microscopy (BEEM) [2]. In this paper, we will discuss the experimental spatial resolution of BEEM, and we will also give some of our BEES results for Au/Si and for Au/PtSi/Si. Our experimental BEEM studies indicate that, for Au/Si, hot electron transport is diffusive rather than ballistic, because the inelastic mean free path length (∼100 nm) is much larger than the elastic mean free path length (∼10 nm). This is in agreement with existing theories and with the literature on the internal photoemission method of studying the transport. Even in this diffusive regime, the spatial resolution of BEEM is still expected to be very good, being on the order of 10 nm [2]. Our preliminary work on PtSi shows that it has an attenuation length of 4 nm, which differs significantly from that of Au.

The theory of the point source low energy electron microscope is reviewed. Images are calculated for a carbon fibre, a small cluster of MgO and a double helix of carbon atoms. A Kirchoff-Helmholtz transform is used for reconstruction. The importance of image size is stressed and the chemical specificity of the method is demonstrated

Atomic force microscopy (AFM) has been used to image the surface atomic structure of hydroxyapatite [Ca10(PO4)6 (OH)2], HA, and brushite [CaHPO4 · 2H2O], DCPD. Compared to HA, the surface of DCPD was found to be much less complex. Identification has been made of one crystal plane of DCPD that has atoms commensurate with those of one of the observed crystal planes of HA.

The near atomic spatial resolution of the atom probe field ion microscope permits the elemental characterization of internal interfaces, grain boundaries and surfaces to be performed in a wide variety of materials. Information such as the orientation relationship between grains, topology of the interface, and the coherency of small precipitates with the surrounding matrix may be obtained from field ion microscopy. Details of the solute segregation may be obtained at the plane of the interface and as a function of distance from the interface for all elements simultaneously from atom probe compositional analysis. The capabilities and limitations of the atom probe technique in the characterization of internal interfaces is illustrated with examples of grain boundaries and interphase interfaces in a wide range of materials including intermetallics, model alloys, and commercial steels.