Columnar Features Research Articles

Correlation of process parameters with morphology and magnetic properties of Co-based amorphous, soft, thin films

The in-plane, dipolar anisotropy of a soft magnetic thin film with columnar growth features is thought to result from the alignment and eccentricity of the column cross sections. This anisotropy can be reduced either by randomizing the alignment of the elliptic axes or by reducing the eccentricity. To determine the origin of the reductions produced by processing variations, we image processed micrographs from transmission electron microscope (TEM) of sequentially sputtered, amorphous CoB alloy thin films, and correlated their in-plane magnetic anisotropies with the statistics of the nanoscale features in their morphologies. The results confirmed that the in-plane anisotropies were dominated by correlations in the alignment of the major axes of the anisotropic growth features. Reduced anisotropies were observed in obliquely deposited films grown under the influence of a substrate bias, even though the eccentricity in their growth features was significantly increased. The effect of the increased eccentricity was apparently overcompensated by a randomization in the orientation of the features of the relaxed film structures.

Gold-Nickel Multilayer Films: Structure-Property Correlations

AbstractGold-nickel multilayer films with periods of 1.2 - 4.6 nm were deposited on silicon substrates by magnetron sputtering, and plan and cross-sectional specimens were examined by transmission electron microscopy. The cross-sectional specimens revealed well-defined layering and columnar growth features that extended through the film thickness. Dark striations extending normal to the layers were attributed to diffraction contrast from defect strain fields. Diffraction patterns showed that the films were highly textured and that short-period films had a single fcc structure, while long-period films separated into three fcc structures. High-resolution images of the layer interfaces showed local regions of epitaxy partitioned by regions of disorder.Indentation tests using a Nanoindenter, a depth-sensing indentation device, were performed to measure the elastic modulus and hardness of the films. No modulus enhancement was detected, and a small variation in hardness was measured.

Stratigraphy and Depositional Environment of Upper Cambrian Red Lion Formation, Southwestern Montana: ABSTRACT

The Red Lion Formation was examined along a northwest-southeast transect from Missoula to Bozeman, Montana. Lateral equivalents are the Snowy Range Formation east of Bozeman and the upper Fishtrap Dolomite in northwest Montana. The basal Dry Creek Member (0-5 m) consists of shale interbedded with quartz siltstones and sandstones. The overlying Sage Member, up to 115 meters in thickness, is characterized by ribbon carbonate beds containing lime mudstone and quartzose calcisiltite couplets arranged in fining-upward sequences 1-5 cm thick. Couplets are interlayered in places with thin (1-5 cm) to medium bedded (6-70 cm) units of laminated and non-laminated calcareous siltstones, flat-pebble conglomerates, trilobite packstones, cryptalgal boundstones, bioturbated lime mudstones and shales. In places, the upper Sage contains columnar and domal algal features. The Red Lion Formation is considered to be one Grand Cycle with the Dry Creek representing a lower inner detrital half-cycle and the Sage an upper carbonate half-cycle. The Dry Creek formed as the result of a westward clastic pulse from the inner detrital belt across an intrashelf basin onto outer middle carbonate peritidal complexes of the underlying Pilgrim Formation. Lower Sage ribbon rocks were deposited in storm-crossed, below wave-base areas. During deposition of the upper Sage, shallowingmore » formed discontinuous algal-peritidal complexes over much of western and central Montana. These complexes were less extensive than earlier Cambrian buildups owing to slower rates of basin subsidence and clastic input suppressing carbonate production.« less

Physical microstructure in device-quality hydrogenated amorphous silicon

The presence of columnar morphology in hydrogenated amorphous silicon in general is well known. However, the existence of such microstructures in films with superior transport properties is not well established. Scanning electron microscopic investigation of intrinsic layers producing high-efficiency solar cells and xerographic devices indicates columnar features and intercolumnar boundaries. The dependence of these features on film thickness and substrate roughness is examined and discussed.

Polycrystalline thin-film CuInSe2/CdZnS solar cells

The fabrication and properties of polycrystalline, CuInSe 2 thin-film solar cells based upon a heterojunction device structure of P-type CuInSe 2 and N-type CdS or mixed CdZnS are described. A photovoltaic conversion efficiency of 11 percent is reported for a CuInSe 2 / CdZnS cell of 1-cm2area when tested under simulated AM1 illumination (ELH lamp). While the highest efficiency cells have been prepared on Mo-metallized, polycrystalline alumina substrates, good cell performance is also presented for cells fabricated on low-cost glass substrates. The vacuum deposited selenide and sulfide films are reported to exhibit strong columnar growth features throughout the critical junction region. The spectral response of the cells is described as being relatively flat from 1100 to 600 nm with very high quantum yields(> 0.8). Photoluminescence emission data on the CuInSe 2 thin-film excited with a He-Ne laser is presented. In general, selenide films producing a good cell performance are reported to exhibit spectra with two or three major broad-band emissions.

Basaltic pillars in collapsed lava-pools on the deep ocean-floor

Observations of peculiar volcanic objects, made by a submersible on the deep sea floor at a depth of about 2,600 m at and near the axis of the East Pacific Rise during the CYAMEX expedition as part of the RITA Project1 are presented here. Two basic types of flow forms were observed within the crestal area of the East Pacific Rise: pillow flows and fluid lavas, the latter sometimes overlying massive flows. The East Pacific Rise at 21° N comprises an axial, unfaulted extrusion zone bordered by an extension zone characterised by faulting2,3. Pillow flows occupy the innermost or extrusion zone and constitute small elongated volcanic highs. Fluid lavas tend to occur at the edge of the adjacent extension zone in bathymetric lows controlled by normal faults or steep primary slopes of constructional highs. In the 50 × 200 m lows which border the extrusion zone the fluid lava is smooth and lobate surfaces which represent the upper surface of the flow are locally collapsed and reveal the internal structure of the fluid lavas. Where the roof collapse is extensive, layered columnar features are visible and volcanic layering can be seen against the flank of the bordering volcanic highs (Figs 1–3). Similar features have been reported from the Galapagos Rift4. The diameter of the approximately cylindrical pillars ranges from 0.5 to 2 m. Some pillars are made of multiple coalescent cylinders. The tops of the pillars are glassy, funnel-shaped and always widening upwards. The pillars were presumed to be hollow from several observations of gashes or openings in the vertical walls of the pillars. This was demonstrated during dive CY 78–19 to the south where a small pillar was toppled by CYANA and subsequent examination revealed a circular canal along the axis of the pillar. The outer surface of the pillars is marked by centimetre-thick glassy, subhorizontal ledges extending several centimetres from the outer vertical surface of the pillars (Figs 2–4). The ledges are spaced every 2–5 cm and show small lava stalactites hanging on the under-side of the ledges. Examination of large layered fragments of pillars recovered by CYANA demonstrated that the layering is only a surface feature as it does not extend through the basaltic mass of the pillars. The apparent layering is due to glass ledges adhering to a vertical basaltic pipe. In some rare instances the pillar outer surface showed no ledges and instead a smooth surface corrugated with vertical grooves. Some pillars are inclined or slightly curved; others get narrower towards the base. The pillars are almost totally aphyric and have the same bulk composition as other lava types recovered in the axial zone of the East Pacific Rise at 21° N (ref. 5).