Thin films were sputter deposited from a Fresnoite (Ba2Si2TiO8) ceramic target at substrate temperatures lower than 175°C. The as-deposited thin films were near amorphous with a void network morphology. In spite of the fact that the film compositions were shifted from stoichiometry, x-ray diffraction studies showed that the films crystallized to form randomly oriented Fresnoite grains. The crystallization kinetics were quite sluggish and the resultant activation energy for the crystallization process was 370 ± 30 kJ/mol. Even after annealing for 10 h at 750°C an appreciable amount of amorphous material remained in the thin films. The short-range order in this amorphous material was changed from that of the as-deposited thin films. The overall devitrification kinetics of amorphous Fresnoite thin films at a fixed temperature were represented theoretically by an equation of Tool's type.

Solid-state amorphization is reported to occur in aluminum-platinum thin films. A uniform amorphous alloy layer was observed at the interface between aluminum and platinum layers for electron beam evaporated samples in an as-deposited state. For a pure aluminum overlayer deposited on top of a coevaporated Al–Pt amorphous alloy, the aluminum dissolves into the amorphous phase leading to a fully amorphous sample. In this last case the amorphization is nonuniform upon low-temperature anneals (T < ≃2 200 °C) and gives rise to hole formation in the aluminum overlayer. Direct observations of this phenomenon during in situ annealing of the thin films in a transmission electron microscope were carried out.

A series of unistructural materials was used to investigate dependence of fracture energy upon crystal bond ionicity. Fracture energy values obtained from indentation measurements were found to agree with those obtained from a simplistic sine function force law calculation. In addition, an indentation procedure to determine whether environments enhance fracture is discussed.

A photoluminescence technique to characterize, for lasing wavelength, the channeled substrate buried heterostructure wafer grown for fabricating lasers for undersea transmission applications, is described. The technique consists of photopumping a piece from the as-grown wafer at 80 K to achieve lasing action and determining the lasing wavelength at 300 K after correcting for the temperature shift of the bandgap. By comparing the optically determined wavelength against the lasing wavelength measured on the device, the accuracy of the technique to predict wavelength is found to be ± 20 nm. The factors that limit the accuracy are discussed.

A silicon single-crystal slab 0.15 mm in thickness was bent to produce small, nonuniform surface strains of the order of 0.2%. The electron channeling patterns were observed in a JSM 840 SEM (scanning electron microscope) at an accelerating voltage close to 25 kV. Proper choice of the triangles formed by intersecting channeling lines of zero-order and of higher-order Laue zones allows one to measure the changes in their dimensions caused by imposed strain. It was estimated that the lower limit of detectable elastic strain is close to 0.1%. The possibilities of using this method for estimation of the average elastic strains in thin epitaxial layers are discussed.

A memory (lock-on) phenomenon was observed in the semiconducting glasses belonging to the As–Se–Te system, and this phenomenon was studied through electrical, calorimetric, and x-ray diffraction methods. The structural characteristics were also correlated to the time it takes to reach the memory state. The growth process in composition As0.40Se0.30Te0.30 exhibited a dependence on electrode polarity in such a way that it began at the positive electrode and finished at the negative one. The growth speed of the conductive filament was found to be approximately 22μm s−1. The crystalline nature of the lock-on filament was confirmed, and the peaks corresponding to the x-ray diffraction pattern of the surface of a sample of composition As0.45 Se0.10Te0.45, partially covered by filaments, correspond to monoclinic As2Te3. The memory effects found agree with those predicted through Ovshinsky's criterion, as the average coordination numbers for the noncrystalline structures of the alloys analyzed are 2.4 and 2.3, respectively.

The electrical resistivity of fluorinated carbon black particles, CFx, is reported as a function of fluorine content, pressure, and temperature. Fluorination does not destroy the aggregate structure of carbon black, but does change its physical properties. The resistivity changes from 10−2 to 10+12 Ω cm as x increases from 0 to 1.2, with a very rapid change occurring in the range 0.08≤x≤0.27. Samples with x = 0 and x = 0.07 exhibit a pressure dependence described by p∝ P−s with s>0. Fully fluorinated samples (x = 1.2) have s≃0. Intermediate compositions have low-pressure regimes where the resistivity is independent of pressure, and high-pressure regimes with s>0. For all samples exhibiting pressure-dependent resistivity, s increases as x increases. For samples with low-fluorine content, the resisitivity increases with decreasing temperature. These observations are interpreted in terms of structure, especially surface structure.

Thin films of Ho1Ba2Cu3O7 − x and Y1Ba2Cu3O7 − x were deposited on SrTiO3 and Al2O3, substrates by pulsed laser deposition of high-Tc bulk superconductor pellets in vacuum. Following annealing in O2 at 800–900 °C the films were superconducting with typical Tc (50%) = 89 K and transition widths of 10 K. Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) were utilized to study the stoichiometry of the as-deposited films for laser energy, densities between 0.11 and 4.5 J cm−2. The films were deficient in holmium and yttrium for energy densities below 0.6 and 0.4 J cm −2, respectively. The films were stoichiometric for fluences above 0.6 J cm−2. In addition, preliminary time dependence and spectroscopic observations of the laser-produced plasma are presented. The results indicate an ablation mechanism that at high energy densities preserves stoichiometry. TEM and x-ray characterization of annealed, superconducting Ho1Ba2Cu3O7 − x films on (100) SrTiO3 showed mixed regions of epitaxially oriented 1:2:3 material with either the c axis or a axis oriented along the surface normal. The a-axis-oriented material grew preferentially in the films with b, c, twinning.

High-densified LiTaO3-type ceramics have been obtained by sintering at 900°C after the addition of small amounts of a LiF + MgF2 mixture. Partial hydrolysis of MgF2 and volatilization of either LiF, LiOH, or Li2O due to hydrolysis and partial substitution of F-ions by (OH−) occur during heat treatment. The ferroelectric Curie temperature Tc increases with the amount of additive. The ceramics have been polarized by heating to Tc and cooling down under a dc field. The piezoelectric and pyroelectric coefficients of such ceramics are approximately 30% and 20% of the corresponding values for a LiTaO3 single crystal.

Nanosecond time-resolved reflectivity and ellipsometry experiments have been performed on (100) Si wafers encapsulated by 5.5–76.2 nm thick thermal oxides, using pulsed KrF (248 nm) laser energy densities sufficient to melt the Si beneath the oxide. Post-irradiation nulling ellipsometry, optical microphotography, and surface profiling measurements were carried out. It was found that the threshold energy density required to melt the Si varies with oxide thickness; this is explained primarily by the reflective properties of the oxide overlayer. The time-resolved reflectivity and ellipsometry measurements show that rippling of the SiO2 layer occurs on the 20–40 ns timescale and results in a decrease in specular reflectivity of the rippled silicon surface beneath. Optical model calculations suggest that pulsed laser annealing through a thick oxide layer results in a damaged near-surface silicon layer (∼ 30 nm thick); this layer contains defects that are probably responsible for the degraded performance of devices.

A procedure for modifying the surface composition of catalytically active metals with silicon-containing gaseous reactants has been developed. This new gas-solid reaction method is unique in that it can be used for the in situ synthesis of catalytically interesting materials, which cannot be done by conventional solid-solid reaction techniques. Using an oxygen-free silicon compound (e.g., hexamethyldisilazane, HMDS), the metals studied fall into two categories: those that involve reaction followed by diffusion, and those that exhibit surface reaction only. The first group, consisting of the metals Ni, V, Rh, Pt and Pd, formed thick (up to 0.6μ) Si diffusion layers, after reaction at 430 °C for a few hours, with either H2/HMDS or Ar/HMDS mixtures. Under the same conditions, the second group of metals, Fe and Co, showed thin (∼ 500 Å) overlayers containing silicon, but with no diffusion. The only nonmetal (graphite) studied so far showed no reaction, within the detectability limits of Auger spectroscopy. This observation shows that these reactions are catalytically induced by certain metal surfaces; in other words, they selectively take place on metals. These findings clearly have important implications for catalysis. For example, the metal surfaces of oxide-supported metal catalysts can, in principle, be selectively modified by gas-phase reactants. This treatment can readily be accomplished in situ in the catalytic reactor. The above reactions may well result in a new class of metallic catalysts, with one of the components being silicon. Furthermore, gas-phase compounds containing the elements aluminum, boron, and germanium are known to react with metals in an analogous manner, which further extends the range of possibilities for the synthesis of new catalytic materials.

Thin films of SnO2−x (0<x<1) were deposited on Corning glass and alumina substrates by employing a pulsed laser evaporation (PLE) technique. The microstructural features of the films were probed with Sn119 conversion electron Mössbaucr spectroscopy (CEMS) whereas the structural characteristics were identified by using low-angle x-ray diffraction measurements. The electrical and optical properties have also been studied. It is shown that films with conductivity of 3 × 102 (ohm·cm)−1 and transmission of 90% can be obtained by appropriate postannealing of the as-deposited films in air and vacuum. The energy gap of this nearly stoichiometric single-phase SnO2 film was found to be 3.5 eV and spectroscopic ellipsometry measurements indicated the refractive index lobe typically between 1.8–1.9 over the wavelength range of 400–800 nm.

The effect of implantation of low-solubility, metallic impurities into Si on the oxidation kineties in steam was studied. The list of impurities that were studied include Ti, Co, Ni, Fe, Yb, Pb, Sn, and Ag. Kinetic data from Pb+ -implanted Si is correlated with the impurity behavior during the oxidation. It will be shown that the oxidation rate is dependent both on the impurity segregation phenomena at the oxide/Si interface and on the nature of the ion-induced damage that is stable at the oxidation temperature. Also, it is shown that novel morphologies can develop in the Si substrate during oxidation. Transmission electron microscopy and Rutherford backscattering/channeling spectroscopy were used to characterize these structures. Mechanisms responsible for the morphological changes in the substrate during oxidation are discussed.

Angle-resolved x-ray photoelectron spectroscopy (ARXPS) results in a very detailed analysis of minor amounts (≥0.3 nm) of interface compounds and their spatial distribution. First experimental results on the Si–SiO2 interface used in microelectronics, are presented. The ARXPS results on plane, single crystalline (100) Si, oxidized to about 5 nm SiO2, indicate a planar Si surface connected by about one monolayer Si∗ to a compressed SiO∗2 layer coated by SiO2. Separated from this interface region, Si clusters stabilized by a compressing SiO∗2 coating have been found in SiO2. Dehydrogenation is showing up in binding energy changes in SiO2 indicating that H or OH is not only saturating Si∗ but is also bonded to SiO2. The O deficiency of amorphous SiO2,x is increasing toward the outer SiO2 surface.

Damage in single-crystal β-SiC(100) as a result of ion bombardment has been studied using Rutherford backscattering/channeling and cross-section transmission electron microscopy. Samples were implanted with Al (130 keV) and Si (87 keV) with doses between 4 and 20 × 1014 cm−2 at liquid nitrogen and room temperatures. Backscattering spectra for He+ channeling as a function of implantation dose were initially obtained in the [110] direction to determine damage accumulation. However, the backscattered yield along this direction was shown to be enhanced as a result of uniaxial implantation-induced strain along [100]. Spectra obtained by channeling along this latter direction were used along with the computer program TRIM to calculate the critical energy for amorphization. The results for amorphization of β-SiC at liquid nitrogen and room temperature are ∼ 14.5 eV/atom and ∼ 22.5 eV/atom, respectively.

Diffusion of 18O in the superconductor La2−x Srx CuO4−y has been measured as a function of x (0 to 0.20) between 300 and 500°C at an oxygen partial pressure of ≍ 1 atm. Concentration profiles were obtained using a secondary ion mass spectrometer. The diffusion coefficient decreases with increasing Sr additions from 0.1 to 0.2, primarily because of an increase in activation energy. This result, which is contradictory to the expectation that the diffusion coefficient should increase with increasing vacancy concentration caused by the added Sr, can be explained if oxygen vacancies are bound to Sr clusters. Measurements on samples with x = 0 or 0.05 were unsuccessful, probably because of porosity.

The effect of hydrogen plasma exposure on the properties of transparent conducting indium-tin oxide films has been studied. The exposure reduces the film surface to elemental indium. The thickness of the reduced layer increases with increasing exposure and finally saturates to a thickness of about 100 nm. The reduced surface is rough and decreases the visible transmittance of these films drastically due to increased absorptance and reflectance. The reduced metal layer decreases the sheet resistance of the films. Annealing of the plasma-exposed film in oxygen recovers the visible transmittance except in the case of the severely damaged films.

Recently it was reported that high quality, 10–100 μm thick, single-crystalline Si films were formed on oxidized single-crystalline Si wafers by the lateral epitaxial growth over oxide (LEGO) process. Although this recrystallization process is reliable and reproducible, periodic regions of dislocations in the otherwise relatively dislocation-free Si film were not well understood. In this paper, therefore, the film stress and defect properties are investigated in detail, and devices made in recrystallized wafers are compared with devices in conventional wafer structures. Stress levels were found to be too low to cause defects, with TEM data suggesting an impurity mechanism (SiO2 precipitation) for small dislocation loops and slight crystalline misorientation for long dislocation lines in the periodic, defective areas. Device results confirmed that LEGO is a viable alternative to the dielectric isolation (DI) technology.

Some observations of laser marking of thin films are presented. Time-resolved reflectivity measurements performed during laser marking of thin organic films indicate that the pit-formation processes start in less than 10 ns after the onset of the laser pulse and that some reversal of the process occurs following exposure termination. Temperature calculations for laser heating of thin films with focused scanning beams explain some of the mark (pit) morphology and material flow behavior that is observed. Scanning electron microscopy (SEM) studies of the marks indicate that at high laser powers, pit formation occurs by ablation and at low laser powers, pits can be formed without ablation. Pits were also formed in a 100nm thin film by resistive heating where the maximum temperature was less than 300 °C.

The ways in which iron may affect the reaction between silicon and nitrogen are summarized and considered both in terms of possible mechanisms of the nitridation process and also in terms of the phases produced by the reaction. Some new results are reported that indicate that, in addition to removing an oxide layer from the silicon, or forming an alloy with the silicon, iron can activate the gaseous nitrogen. Other impurities, such as hydrogen in the gas, may also modify the behavior of nitrogen.