Solid/melt interface studies of high-speed silicon sheet growth

Radial growth-rate anisotropies and limiting growth forms of point nucleated, dislocation-free silicon sheets spreading horizontally on the free surface of a silicon melt have been measured for (100), (110), (111), and (112) sheet planes. Sixteen-millimeter movie photography was used to record the growth process. Analysis of the sheet edges has lead to predicted geometries for the tip shape of unidirectional, dislocation-free, horizontally growing sheets propagating in various directions within the above-mentioned planes. Similar techniques were used to study polycrystalline sheets and dendrite propagation. For dendrites, growth rates on the order of 2.5 m/min and growth rate anisotropies on the order of 25 were measured

Growth of silicon carbide crystals on a seed while pulling silicon crystals from a melt

A saturated solution of silicon and an element such as carbon having a segregation coefficient less than unity is formed by placing a solid piece of carbon in a body of molten silicon having a temperature differential decreasing toward the surface. A silicon carbide seed crystal is disposed on a holder beneath the surface of the molten silicon. As a rod or ribbon of silicon is slowly pulled from the melt, a supersaturated solution of carbon in silicon is formed in the vicinity of the seed crystal. Excess carbon is emitted from the solution in the form of silicon carbide which crystallizes on the seed crystal held in the cool region of the melt

High-purity silicon crystal growth

Crystal growth parameter effects on minority carrier lifetime and solar cell efficiencies were investigated using high purity techniques such as float zoning. Study objectives include the following: (1) optimize dopants and minority carrier lifetime in FZ material for high efficiency silicon solar cell applications; (2) improve the understanding of lifetime degradation mechanisms (point defects, impurities, thermal history, surface effects, etc.), and (3) crystallographic defect characterization of float zone and ribbon crystals via X-ray topography

Silicon ribbon growth by a capillary action shaping technique

The technique of silicon ribbon growth by the capillary action shaping is assessed for applicability to photovoltaic power device material. Ribbons 25 mm in width and up to 0.5 m in length have been grown from SiC dies, and some new characteristics of growth from such dies have been identified. Thermal modifiers have been studied, and systems were developed which reduce the frozen-in stress un silicon ribbons and improve the thickness uniformity of the ribbons. Preliminary spreading resistance measurements indicate that neither surface striations nor twin boundaries give rise to appreciable resistivity variations, but that large-angle grain boundaries cause local resistivity increases of up to 200%

Infant feeding practices and nut allergy over time in Australian school entrant children

Aim. To measure the association between infant feeding practices and parent-reported nut allergy in school entrant children. Method. The Kindergarten Health Check Questionnaire was delivered to all 110 Australian Capital Territory (ACT) primary schools between 2006 and 2009. Retrospective analyses were undertaken of the data collected from the kindergarten population. Results. Of 15142 children a strong allergic reaction to peanuts and other nuts was reported in 487 (3.2%) and 307 (3.9%), children, respectively. There was a positive association between parent reported nut allergy and breast feeding (OR = 1.53; 1.11–2.11) and having a regular general practitioner (GP) (OR = 1.42; 1.05–1.92). A protective effect was found in children who were fed foods other than breast milk in the first six months (OR = 0.71; 0.60–0.84). Conclusion. Children were at an increased risk of developing a parent-reported nut allergy if they were breast fed in the first six months of life

The Middle English suffix -ish: Reasons for decline in productivity

The aim of the present paper is to investigate the reasons for the significant decline in both the frequency and productivity of the suffix -ish in Middle English. The major factors responsible seem to be the growing popularity of the of + Noun phrases as well as the competition among -ish and other suffixes. The analysis will be preceded with the introduction of some essential facts concerning the semantic development and productivity of the OE suffix -isc in Middle English

Three-terminal devices to examine single molecule conductance switching

We report electronic transport measurements of single-molecule transistor devices incorporating bipyridyl-dinitro oligophenylene-ethynylene dithiol (BPDN-DT), a molecule known to exhibit conductance switching in other measurement configurations. We observe hysteretic conductance switching in 8% of devices with measurable currents, and find that dependence of the switching properties on gate voltage is rare when compared to other single-molecule transistor devices. This suggests that polaron formation is unlikely to be responsible for switching in these devices. We discuss this and alternative switching mechanisms.Comment: 5 pages, 4 figures. Supporting material available upon reques

Ni-Cr textured substrates with reduced ferromagnetism for coated conductor applications

A series of biaxially textured Ni(1-x)Cr(x) materials, with compositions x = 0, 7, 9, 11, and 13 at % Cr, have been studied for use as substrate materials in coated conductor applications with high temperature superconductors. The magnetic properties were investigated, including the hysteretic loss in a Ni-7 at % Cr sample that was controllably deformed; for comparison, the loss was also measured in a similarly deformed pure Ni substrate. Complementary X-ray diffraction studies show that thermo-mechanical processing produces nearly complete {100} cube texturing, as desired for applications.Comment: PDF only; 19 pp., incl 10 figure

Degree of grammaticalisation of behind, beneath, between and betwixt in Middle English

The analysis shows that while behind and beneath are still frequently used as adverbs in the whole Middle English period, between and betwixt are predominantly used as prepositions already in Early Middle English. This clearly demonstrates that the degree of grammaticalisation of the latter two Middle English words was much higher than that of behind and beneath

Silicon ribbon growth by a capillary action shaping technique

The crystal growth method described is a capillary action shaping technique. Meniscus shaping for the desired ribbon geometry occurs at the vertex of a wettable die. As ribbon growth depletes the melt meniscus, capillary action supplies replacement material. A capillary die is so designed that the bounding edges of the die top are not parallel or concentric with the growing ribbon. The new dies allow a higher melt meniscus with concomitant improvements in surface smoothness and freedom from SiC surface particles, which can degrade perfection