The mechanical deflection of cantilever microbeams is presented as a new technique for testing the mechanical properties of thin films. Single-layer microbeams of Au and SiO2 have been fabricated using conventional silicon micromachining techniques. Typical thickness, width, and length dimensions of the beams are 1.0,20, and 30 μm, respectively. The beams are mechanically deflected by a Nanoindenter, a submicron indentation instrument that continuously monitors load and deflection. Using simple beam theory and the load-deflection data, the Young's moduli and the yield strengths of thin-film materials that comprise the beams are determined. The measured mechanical properties are compared to those obtained by indenting similar thin films supported by their substrate.

The 29Si chemical shielding parameters derived from 29Si nuclear magnetic resonance (NMR) spectra of 25 silicides of Group IVB, VB, VIB, VIIB, and VIII metals are presented. The isotropic shifts of these silicides span the range from −1650 to + 925 ppm, relative to TMS, and have shielding anisotropies −250 to + 335 ppm; these extremes are approximately ten times as large as those of organosilicon and silicon oxide compounds. For silicides of Ti, Zr, Nb, Ta, Cr, Mo, W, Rh, Ni, Pd, Pt, and Cu, the chemical shielding interaction is sufficiently larger than the extraneous spectral broadening to allow detection of multiple phases owing to different crystal structures and local differences in stoichiometry. The potential to detect multiple phases in silicides of Hf, V, Mn, Fe, Ru, and Co is less owing to smaller differences in isotropic shifts and/or broadening that overwhelms the chemical shielding information. However, it is possible that the broadening is not an inherent property of these silicides, but rather, suggests the presence of structural defects in these particular samples.

An ultra high vacuum system has been designed and constructed for the purpose of depositing high-quality oxide films on well-characterized crystal surfaces at low temperatures. In particular, aluminum phosphorus oxide films have been deposited on both In P and Ge surfaces for the purpose of device application. Electrical measurements of metal-oxide-semiconductor structures show much improved interfacial properties with little or no hysteresis.

Bond counting, and calculations of entropy, bond, and bond angle strain have been used to evaluate the relative stability of diamond and graphite on various substrates for conditions that normally stabilize the graphite structure in bulk. Pseudomorphic and many metallic substrates that bond to carbon when clean are found to stabilize the diamond phase; others stabilize the graphite phase. If the relative thermodynamic stability governs the kinetics of growth under film deposition conditions, then an interesting prediction of the present research is that growth of diamond on {100} surfaces should proceed by formation of surface monolayers that alternately have graphite and diamond bonding configurations, and with the graphite monolayer converting to a diamond configuration when it becomes subsurface. The latter mode of growth should not occur in an atomic hydrogen atmosphere, nor should it occur on {111} surfaces.

Electrohydrodynamic atomization'has been adapted to produce Al2O3 powders ranging in size from 10 nm to 300 μm. Microstructural characterization using x-ray diffraction, scanning, and transmission electron microscopy reveals changes in phase selection as a function of particle size, hence supercooling. Amorphous powders are common below 100 nm in diameter. Cubic spinel γ is found in single phase form between 100 nm and 2μm, and partially transformed to δ between 2 and 20 μm. There is also evidence of σ and θ or a precursor of θ forming directly from the liquid above 5 μm. The stable corundum structure is consistently found above 20 μm but exhibits three different morphologies: faceted, dendritic, and cellular. Phase selection is examined on the basis of fundamental thermodynamic and kinetic considerations and results from computer models predicting the thermal history of the powders. It is concluded that metastable phases require the elimination of catalytic sites for the nucleation of a and are thus more likely to form in the smaller powders. Furthermore, submicron powders achieve sufficiently high cooling rates to preserve the metastable phases formed (γ), but those higher than ∼ 1 μm experience a thermal excursion long enough to transform γ to more stable forms of Al2O3.

In situ Raman spectra were taken, between 800 and 1200 cm−1, on films of polypyrrole during both the electrochemical growth and the reduction reactions. During the reduction reaction we observed a frequency shift of approximately 10 cm−1 of two in-plane vibrational modes. We attribute these shifts to the bond conjugational defects induced by doping and undoping of the polypyrrole films. A quantitative model for this phenomenon based on normal mode calculations is presented. The electrical conductivity and thermopower of polypyrrole doped with tetrafluoroborate and iron chloride ions is also reported for temperatures between 10 and 350K.

The crystallizing phases from a BaZn YbTh fluoride glass were a BaYbTh fluoride, ZnF2, and YbF3, as identified with x-ray diffraction and composition-enhanced scanning electron microscopy. Blocky BaYbTh fluoride crystallizes first, at about 450 °C, and ZnF2 excluded from this phase crystallizes at its surfaces. At higher temperatures the BaYbTh fluoride phase decomposes partially to BaThF6 and YbF3 phases. The kinetics and temperatures of crystallization were also followed with differential scanning calorimetry.

Polyimide-metal oxide (Co3O4 or CuO) composite films have been prepared via in situ thermal decomposition of cobalt (II) chloride or bis (trifluoroacetylacetonato) copper (II). A soluble polyimide (XU-218) and its corresponding prepolymer (polyamideacid) were individually employed as the reaction matrix. The resulting composites exhibited a greater metal oxide concentration at the air interface with polyamideacid as the reaction matrix. The water of imidization that is released during the concurrent polyamide acid cure and additive decomposition is believed to promote metal migration and oxide formation. In contrast, XU-218 doped with either HAuCl4 · 3H2O or AgNO3 yields surface gold or silver when themolyzed (300 °C).

Alumina films, 160 nm thick, were deposited on (100) -oriented silicon single-crystal substrates by pyrohydrolysis of aluminum chloride. Such films are candidate gate materials for an improved pH ion-sensitive field-effect transistor (pH-ISFET) for industrial and medical pH measurements. The current-voltage (I–V) characteristics of films annealed for 30 min at temperatures of 850, 1000, and 1175 °C were determined, Annealing at 850 °C produced the optimum I–V behavior for the aluminum oxide pH-sensitive films as evidenced by minimum leakage current and maximum breakdown voltage. The structures of the annealed films were examined using transmission electron microscopy. The anneals at 1000 and 1175 °C caused partial and complete transformation, respectively, of the as-deposited α-alumina to the α-alumina phase. Associated with a-alumina formation was the creation of voids along the grain boundaries and in the grain interiors that provided paths of increased electrical conduction through the alumina films and degraded their dielectric behavior.

Cubic boron nitride (C–BN)' powders admixed with graphite-structured boron nitride powder (g-DN), silicon carbide whisker (SCW), or silicon nitride whisker (SNW) were shock compacted to pressures up to 22 GPa. Unlike previous work with diamond and graphite [D. K. Potter and T. J. Ahrens, J. Appl. Phys. 63, 910 (1987) it was found that the addition of g-BN inhibited dynamic consolidation. Good consolidation was achieved with a 4–8 μm particle size C–BN powder admixed with 15 wt.% SNW or 20 wt.% SCW whereas a 37–44 μm particle size C–BN mixture was only poorly consolidated. Scanning electron microscopy (SEM) analysis demonstrates that SCW and SNW in the mixtures were highly deformed and indicated melt textures. A skin heating model was used to describe the physics of consolidation. Model calculations are consistent with SEM analysis images that indicate plastic deformation of SCW and SNW. Micro-Vickers hardness values as high as 50 GPa were obtained for consolidated C–BN and SNW mixtures. This compares to 21 GPa for single-crystal Al2O3 and 120 GPa for diamond.

The mechanisms of steady-slate creep in compression in a sintered SiC produced via sintering of β-SiC powders derived from gaseous reactants in a plasma are have been determined from (1) kinetic data within the ranges of temperature and constant stress of 1770–2020 K and 17–208 MPa, respectively, and (2) the results of transmission electron microscopy (TEM) and other microbeam characterization techniques. The stress exponent was 2.06 ± 0.04; the values of activation energy were 913 ± 13 and 630 ± 14 kJ/mol above and below, respectively, a knee of ∼∼ 1920 K. Gliding dislocations and B4C precipitates, which developed within the grains during creep, and their interaction were the dominant microstructural features of the crept material. Apparent nonmechanical pinning of the dislocations at the precipitates indicated that the latter attracted the dislocations rather than acting as classical obstacles to dislocation movement. A synthesis of this information leads to the conclusion that the controlling creep mechanisms in this SiC were grain boundary sliding accommodated by grain boundary diffusion at T < 1920 K and lattice diffusion at T > 1920 K. The parallel mechanism of dislocation glide also contributed to the total strain.

The close-spaced vapor transport (CSVT) is an efficient and cost-effective technique that allows the growth of polycrystalline as well as epitaxial thin layers of semiconductors. The close spacing between a source and a substrate, introduced in 1963 as a special feature in the vapor phase method, has been applied to about 18 semiconductors with a special focus on CdTe and GaAs. This paper reviews the close-spaced technique, the models presented to explain the film growth rates, the transport reactions, and film characteristics for all the semiconductors that have been obtained by CSVT. All-thin-film structures for solar cells or other applications are certainly feasible with the use of the CSVT technique when a good lattice matching exists between the successive layers.

The cracking and decohesion of thin films can be characterized by critical values of a nondimensional parameter governed by the residual stress, the film thickness, and a fracture resistance. This article reviews the status of understanding concerning the magnitude of this number for various types of adherent film on either brittle or ductile substrates. Important effects of elastic properties, substrate thickness, and yield strength are described.