The properties of thin Y2O3 films grown using an in situ ultraviolet (UV)-assisted pulsed laser deposition (PLD) technique were studied. With respect to Y2O3 films grown by conventional PLD under similar conditions but without UV illumination, the UVPLD-grown films exhibited better structural and optical properties, especially for lower substrate temperatures, from 340 to 400 °C. These layers were highly crystalline and textured along the (111) direction, and their refractive index values were similar to those of reference Y2O3 layers. They also exhibited a better stoichiometry and contained less physisorbed oxygen than the conventional PLD-grown layers.

A metalorganic precursor containing Ti and Pt was synthesized using Ti alkoxide derivative, amino acid, and platinum salt. The decomposition behavior of the precursor and thin-film formation were examined in terms of microstructure evolution and crystallization. The precursor yielded anatase at 400 °C. Grain growth of platinum particles and TiO2 grains was suppressed even at 800 °C in the films. Suppression of grain growth was attributed to an effect of film thickness.

The original equation of Spence and Taftø for quantitative determination of site occupancy using atom location by channeling enhanced microanalysis method has been extended to take into account both delocalization effect and the influence of point defects (antisite atomic distribution and vacancies). The outcome of this treatment suggests that, for crystals free of antisite defects, the accuracy of site occupancy is influenced by delocalization effect but is independent of both thermal and structural vacancies. For crystals free of structural vacancies, the accuracy of site occupancy is influenced by both delocalization effect and antisite defects, but is independent of thermal vacancies. The delocalization effect was shown to vary with channeling strength at a given channeling condition. For a binary ordered phase in which at least one of the host elements exhibits weak delocalization effect (as is the case for many transition-metal aluminides), a tangent-line method for obtaining the value of k (a parameter necessary for the calculation of site occupancy) was proposed, allowing the determination of the delocalization correction factor for the other host element. Application of this method to estimating the delocalization effect of Al in Ti3Al and TiAl under axial and planar channeling conditions, respectively, was demonstrated.

With the advent of copper metallization in interconnect structures, new barrier layers are required to prevent copper diffusion into adjacent dielectrics and the underlying silicon. The barrier must also provide adequate adhesion to both the dielectric and copper. While Ta and TaN barrier layers have been incorporated for these purposes in copper metallization schemes, little quantitative data exist on their adhesive properties. In this study, the critical interface fracture energy and the subcritical debonding behavior of ion-metal-plasma sputtered Ta and TaN barrier layers in Cu interconnect structures were investigated. Specifically, the effects of interfacial chemistry, Cu layer thickness, and oxide type were examined. Behavior is rationalized in terms of relevant reactions at the barrier/dielectric interface and plasticity in adjacent metal layers.

In this paper we evaluate the in-depth homogeneity of GaN epilayers and the influence of electric field present in strained GaN/AlGaN heterostructures and quantum wells on the yellow and “edge” emission in GaN and AlGaN. Our depth-profiling cathodoluminescence measurements show an increased accumulation of defects at the interface. Inhomogeneities in the doping level are reflected by the enhancement of the yellow emission in the interface region. The piezoelectric effect is found to strongly reduce the emission from the strained AlGaN quantum-well barriers. We also show that Ga droplets, commonly found on surfaces of samples grown in Ga-rich conditions, screen the internal electric field in a structure and thus result in a local enhancement of the edge emission intensity.

As-deposited and annealed tantalum films, grown by plasma-promoted chemical vapor deposition (PPCVD) using pentabromotantalum and hydrogen as coreactants, were evaluated as diffusion barriers in copper metallization. Stacks consisting of 500-nm-thick sputtered Cu/55-nm-thick untreated PPCVD Ta/Si were annealed in argon in the range 450 to 650 °C, in 50 °C intervals, along with sputtered Cu/preannealed PPCVD Ta/Si and sputtered Cu/sputtered Ta/Si stacks of identical thickness. Pre- and postannealed stacks were characterized by x-ray photoelectron spectroscopy, Auger electron spectroscopy, Rutherford backscattering spectrometry, hydrogen profiling, x-ray diffraction, atomic force microscopy, sheet resistance measurements, and Secco chemical treatment and etch-pit observation by scanning electron microscopy. The sputtered and preannealed PPCVD Ta films acted as viable diffusion barriers up to 550 °C, while the as-deposited PPCVD Ta films failed above 500 °C. In all cases, breakdown occurred through the migration of Cu into Si, rather than an interfacial reaction between Ta and Si, in agreement with previously reported results for sputtered Ta films. The accelerated barrier failure for as-deposited PPCVD Ta might have been caused by the presence of approximately 20 at.% hydrogen in the as-deposited PPCVD Ta, an observation which was supported by the enhanced performance of the same PPCVD Ta films after annealing-induced hydrogen removal.

Nanocomposite ceramic materials were fabricated by conventional sintering of composite powders obtained by sol-gel coating of submicron powders. The microstructure of these MgAl2O4–ZrO2 materials was studied by transmission electron microscopy. All zirconia grains were in the tetragonal phase. In addition, the intragranular zirconia crystals exhibited heteroepitaxial orientation relationships with the surrounding spinel grains, (hkl)zirconia//(hkl)spinel. Semi-coherent interfaces along {111} planes were observed by high-resolution microscopy. The transformation toward the orthorhombic or the monoclinic phase retained the epitaxial relationships as far as possible. The presence of such heteroepitaxial intragranular crystals in sintered ceramic materials, which did not involve a melting stage, was attributed to the specificity of the material preparation process.

Magnetization measurements, transmission electron microscopy (TEM), and high-resolution micro-x-ray fluorescence (μ-XRF) using a synchrotron radiation source (Advanced Photon Source) were used to examine Fe3O4 particle agglomerates of nominally 10-nm particles at low concentrations (down to 0.03%) in thick epoxy resin samples. The magnetization measurements showed that at low concentrations (<0.5%) the magnetite particles, although closely packed in the agglomerates, did not interact magnetically. Predicated on a 2-μm sample step scan, the μ-XRF results were compatible with the presence of spherical agglomerates due to magnetostatic attraction, and these ranged in size from 100 to several thousand nanometers, as observed in TEM measurements. At smaller step scans the resolution could be significantly improved. Thus, the synchroton μ-XRF method was very useful in detecting very small concentrations of particles in thick samples and could probably be used to detect particles in amounts as low as 10−16 g.

The ensuing paper summarizes an investigation on the effect of target microstructural morphology on resultant sputter deposited media magnetic performance. Significant differences in media magnetic coercivity were obtained from Co–Cr–Pt–Ta targets possessing the same chemistry, sputtered under identical conditions, but possessing different microstructural phase and crystallographic texture characteristics. This result was most likely caused by the difference in sputter yields for the Ta-containing phases in the two distinct target microstructures. Results support enhanced chromium segregation yielding a decrease in the intergranuler exchange energy field for the deposited thin films.

The influence of the carbon network structure of polycrystalline diamond films that were prepared from a mixture of H2, CH4, and N2 using microwave-enhanced plasma chemical vapor deposition on electron field emission has been systematically investigated. With increasing nitrogen gas flow ratio of [ N2]/[H2 + CH4 + N2], the film hardness and surface roughness of the as-grown films decreased, and the concentration ratio of amorphous sp2-bonded carbon clusters and mixed sp2−sp3 carbon structures to tetrahedrally bonded amorphous carbon phases increased. Correspondingly, the turn-on voltage for electron emission decreased. After the surface post-treatment by pure hydrogen plasma exposure, the concentration ratio was clearly found to have increased dramatically and the turn-on voltage decreased significantly for the films produced at small nitrogen flow ratio. Our results suggest that the influence of the concentration ratio on electron field emission is much more significant than that of the surface roughness of the polycrystalline diamond films studied in this paper.

Well-aligned carbon nitride nanotubes were prepared with a porous alumina membrane as a template when using electron cyclotron resonance (ECR) plasma in a mixture of C2H2 and N2 as the precursor with an applied negative bias to the graphite sample holder. The hollow structure and good alignment of the nanotubes were verified by field-emission scanning electron microscopy. Carbon nitride nanotubes were transparent when viewed by transmission electron microscopy, which showed that the nanotubes were hollow with a diameter of about 250 nm and a length of about 50–80 μm. The amorphous nature of the nanotubes was confirmed by the absence of crystalline phases arising from selected-area diffraction patterns. Both Auger electron microscopy and x-ray photoelectron spectroscopy spectra indicated that these nanotubes are composed of nitrogen and carbon. The total N/C ratio is 0.72, which is considerably higher than other forms of carbon nitrides. No free-carbon phase was observed in the amorphous carbon nitride nanotubes. The absorption bands between 1250 and 1750 cm−1 in Fourier transform infrared spectroscopy provided direct evidence for nitrogen atoms, effectively incorporated within the amorphous carbon network. Such growth of well-aligned carbon nitride nanotubes can be controlled by tuning the ECR plasma conditions and the applied negative voltage to the alumina template.

Time-of-flight measurements performed on micron-thick films of liquid-crystalline zinc octakis(β-octoxyethyl) porphyrin indicated that charge carriers possess significantly high drift mobilities, attaining approximately 0.01 cm2 V−1s −1 and 0.008 cm2 V−1s −1 for holes and electrons, respectively, at room temperature. Upon heating the samples from 300 to 420 K, causing the porphyrin to go from the solid-crystalline to the discotic mesophase, the mobilities did not decrease drastically, and remained at values slightly larger than half those observed at room temperature. Charge transport in this material conformed to the Scher–Montroll model, which attributes a distribution of hopping times to the propagation of the initially formed charged carrier packet. Analysis of the “universal” plots prescribed by this model yielded a dispersion factor of 0.5 for both charge carriers.

Atomic positional disorder of a single-phase natural carbonate fluorapatite (francolite) is revealed from analysis of the atomic displacement parameters (ADPs) refined from neutron powder diffraction data as a function of temperature and carbonate content. The ADPs of the francolite show a strong disturbance at the P, O3, and F sites. When it is heat treated to partially or completely remove the carbonate, the ADPs as well as the other structural parameters resemble those of a fluorapatite (Harding pegmatite) that was measured under the same conditions. The various structural changes are consistent with a substitution mechanism whereby the planar carbonate group replaces a phosphate group and lies on the mirror plane of the apatite structure.

The role of Fe2O3in the structural and physical properties of ternary lead vanadium iron glass system has been studied in comparison with the binary lead vanadate glasses. X-ray diffraction, scanning electron microscopy, and differential thermal analysis show that homogeneous glasses of composition 10Fe2O3 · xV2O5 · (90 − x)PbO can be obtained for x = 50 to 80 mol%. Observation from the infrared spectroscopy shows that the basic building blocks of these glasses are same as those of crystalline V2O5, while differential thermal analysis and electrical conduction of these glasses suggest that there is a strong role of iron, both in the glass network and in the conduction mechanism for the glasses containing a low percentage of vanadium.

The domain structure of bulk periodically poled lithium niobate crystals were analyzed by different techniques. Images of topography, electrostatic force, and piezoelectric response were studied by scanning force microscopy. All these images showed the domain structure of the samples. The electrostatic force was always attractive pointing to a dielectric origin. The diffraction of a laser beam by the periodic structures was also observed, denoting a periodic change of refractive index. From the angle of diffraction the domain spatial frequency was directly obtained. The topographic profile of etched samples was studied by both scanning force and scanning electron microscopy.

A detailed study on the sintering behavior of zirconium diboride powder produced by the self-propagating high-temperature synthesis (SHS) process was carried out in the temperature range of 1500–1800 °C. The fine powder prepared by the SHS process exhibited excellent sinterability and could be sintered at 1800 °C for 1 h to approximately 94% of the theoretical density. The apparent activation energy of densification in the range of 1500–1800 °C was estimated to be 248 ± 4 kJ mol−1. A zirconium dioxide layer formed on the surface of the sintered body and was attributed to boron oxide formation during sintering and concurrent surface oxidation by the oxygen generated from the reduction of boron oxide in the carbonaceous atmosphere. Sintering aids like Fe and Cr appeared to help in densification of ZrB2 powder.

The degradation behavior of integrated Pt/SrBi2Ta2O9/Pt capacitors caused by hydrogen impregnation during the spin-on glass (SOG)-based intermetal dielectric (IMD) process was investigated. SOG was tested as an IMD since it offers better planarity for multilevel metallization processes compared to other SiO2 deposition methods. It was found that the SOG itself does not degrade the ferroelectric performance. Deposition of an under-layer of SiOxNy by plasma-enhanced chemical vapor deposition (PECVD) using SiH4 + N2O + N2 source gases and a SiO2?x capping layer by another PECVD process using SiH4 + N2O source gases produced hydrogen as a reaction by-product. The hydrogen diffused into the SBT layer and degraded the ferroelectric performance during subsequent annealing cycles. A very thin (10 nm) Al2O3 layer grown by atomic layer deposition before the IMD process successfully blocked the impregnation of the hydrogen. Therefore, excellent ferroelectric performance of the SBT capacitors were maintained after the multilevel metallization process as well as passivation. The adoption of SOG in the IMD process greatly improved the surface flatness of the wafer resulting in a higher capacitor yield with very good uniformity in ferroelectric properties over the 8-in.-diameter wafer.

The effect of crystallization on microwave dielectric properties of cordierite glasses containing B2O3 and P2O5 additions was investigated. Two glasses containing 5 wt% B2O3/5 wt% P2O5 and 7.5 wt% B2O3/7.5 wt% P2O5 were studied. Both glasses were sintered to nearly full density at temperatures as low as 860 °C. The frequency constant and quality factor of α cordierite are, respectively, about five times and two times larger than those of glassy phase and μ cordierite. The temperature coefficients of resonant frequency are estimated to be about −13, −55, and −15 ppm/°C for glassy phase, μ cordierite, and α cordierite, respectively. As a result of the microwave dielectric properties of the individual phase, cordierite glasses containing α cordierite possess the best microwave properties.

High-field and high-pressure behavior of microwave-prepared xCuO:(45−x) PbO: 55V2O5 (x = 0 to 20) glasses were investigated for the first time. It was found that the addition of CuO significantly alters the nonlinear I–V characteristics of these glasses; while the glasses with x = 10 exhibit a current-controlled negative resistance behavior associated with a memory type transition, glasses with x = 15 show a threshold-type behavior. Remarkable differences were also noticed in the high-pressure electrical resistivity behavior between the low- and high-CuO-containing glasses. Corroborative thermal, electrical, microscopic, and spectroscopic measurements were carried out to understand the structure–property relations. A structural model was proposed, which is based on the chemical nature of the constituents present in the glasses. The model accounts well for the various observed properties of these glasses.

This work was directed toward developing a database for the long-term reliability of the transverse piezoelectric coefficient d31 under both unipolar and bipolar drive. Under unipolar drive, the films showed excellent reliability, with 99% of the devices surviving to 109 cycles. However, both aging and low amplitude bipolar drive resulted in rapid degradation of d31 due to backswitching of the ferroelectric domains. Both thermal and ultraviolet (UV) imprint prevented backswitching and resulted in improved aging and bipolar degradation behavior. Additionally, the UV imprinted samples showed nonlinear aging due to the presence of an internal space charge field that developed from photo-induced charge carriers.