Semiconductors, polymeric

Use Organic preparations, phosphonium halides, doping agent for n-type semiconductors, polymerization initiator, condensation catalyst. Note A synthetic dye, chrysaniline yellow, is sometimes called phosphine. 

MAJOR USES Insecticide for grain fumigation, animal feeds and tobacco rodenticide doping agent for n-type semiconductors polymerization inhibitor condensation catalyst synthesis of flame retardants for cotton fabrics. 

Polymers are only marginally important in main memories of semiconductor technology, except for polymeric resist films used for chip production. For optical mass memories, however, they are important or even indispensable, being used as substrate material (in WORM, EOD) or for both substrate material and the memory layer (in CD-ROM). Peripheral uses of polymers in the manufacturing process of optical storage media are, eg, as binder for dye-in-polymer layers or as surfacing layers, protective overcoatings, uv-resist films, photopolymerization lacquers for repHcation, etc. 

A mixture of (C H ) , TiCl, and AlCl is useful for polymerizing C —olefins (85). The dimerization of propylene is accompHshed by using catalysts such as Ni(PR2)4 (86). Alkylphosphines such as / fZ-butylphosphine [2501-94-2] have been proposed as a substitute for high purity phosphine in the production of the semiconductor gallium phosphide (87). 

Tertiary stibines have been widely employed as ligands in a variety of transition metal complexes (99), and they appear to have numerous uses in synthetic organic chemistry (66), eg, for the olefination of carbonyl compounds (100). They have also been used for the formation of semiconductors by the metal—organic chemical vapor deposition process (101), as catalysts or cocatalysts for a number of polymerization reactions (102), as ingredients of light-sensitive substances (103), and for many other industrial purposes. 

Boron Bromide. Approximately 30% of BBr produced in the United States is consumed in the manufacture of proprietory pharmaceuticals (qv) (7). BBr is used in the manufacture of isotopicaHy enriched crystalline boron, as a Etiedel-Crafts catalyst in various polymerization, alkylation, and acylation reactions, and in semiconductor doping and etching. Examples of use of BBr as a catalyst include copolymerization of butadiene with olefins (112) polymerization of ethylene and propylene (113), and A/-vinylcarbazole (114) in hydroboration reactions and in tritium labeling of steroids and aryl rings (5). 

The cadmium chalcogenide semiconductors (qv) have found numerous appHcations ranging from rectifiers to photoconductive detectors in smoke alarms. Many Cd compounds, eg, sulfide, tungstate, selenide, teUuride, and oxide, are used as phosphors in luminescent screens and scintiUation counters. Glass colored with cadmium sulfoselenides is used as a color filter in spectroscopy and has recently attracted attention as a third-order, nonlinear optical switching material (see Nonlinear optical materials). DiaLkylcadmium compounds are polymerization catalysts for production of poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVA), and poly(methyl methacrylate) (PMMA). Mixed with TiCl, they catalyze the polymerization of ethylene and propylene. 

Single-crystal samples of conductors best other solid samples are suitable, including polycrystalline metals, polymeric materials, semiconductors, and insulators, ultrahigh vacuum compatible typically > 5 mm diameter, 1-3 mm thick... 

J. Kanicki, Polymeric Semiconductor Contacts and Photovoltaic Applications in Handbook of Conducting Polymers (Ed. T. Skolheim), Dekker, New York 1986. 

More recently. Gamier and coworkers used a printing technique to make OFETs on polymeric substrates [61]. Although printable field-effect transistors based on inorganic semiconductors have been reported as early as 1967 ]62], they did not come to any commercial development. We note, however, that in Gar-nier s device only the electrodes were actually printed. 

Several attempts to use otganic polymeric semiconductors as the active component in photovoltaic devices have been reported during the last two decades. Interest in the photovoltaic properties of conjugated polymers like polyacelylcne, various derivatives of polythiophenes and poly(para-phenylene vinylene)s arose from... 

In addition to chemical reactions, the isokinetic relationship can be applied to various physical processes accompanied by enthalpy change. Correlations of this kind were found between enthalpies and entropies of solution (20, 83-92), vaporization (86, 91), sublimation (93, 94), desorption (95), and diffusion (96, 97) and between the two parameters characterizing the temperature dependence of thermochromic transitions (98). A kind of isokinetic relationship was claimed even for enthalpy and entropy of pure substances when relative values referred to those at 298° K are used (99). Enthalpies and entropies of intermolecular interaction were correlated for solutions, pure liquids, and crystals (6). Quite generally, for any temperature-dependent physical quantity, the activation parameters can be computed in a formal way, and correlations between them have been observed for dielectric absorption (100) and resistance of semiconductors (101-105) or fluidity (40, 106). On the other hand, the isokinetic relationship seems to hold in reactions of widely different kinds, starting from elementary processes in the gas phase (107) and including recombination reactions in the solid phase (108), polymerization reactions (109), and inorganic complex formation (110-112), up to such biochemical reactions as denaturation of proteins (113) and even such biological processes as hemolysis of erythrocytes (114). 

Thermally-Driven Buoyancy Flow. Thermal gradients can Induce appreciable flow velocities in fluids, as cool material is pulled downward by gravity while warmer fluid rises. This effect is Important in the solidification of crystals being grown for semiconductor applications, and might arise in some polymeric applications as well. To illustrate how easily such an effect can be added to the flow code, a body force term of pa(T-T ) has been added to the y-coraponent of the momentum equation, where here a is a coefficient of volumetric thermal expansion. 

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