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Chemical plasma activated

In most cases, CVD reactions are activated thermally, but in some cases, notably in exothermic chemical transport reactions, the substrate temperature is held below that of the feed material to obtain deposition. Other means of activation are available (7), eg, deposition at lower substrate temperatures is obtained by electric-discharge plasma activation. In some cases, unique materials are produced by plasma-assisted CVD (PACVD), such as amorphous siHcon from silane where 10—35 mol % hydrogen remains bonded in the soHd deposit. Except for the problem of large amounts of energy consumption in its formation, this material is of interest for thin-film solar cells. Passivating films of Si02 or Si02 Si N deposited by PACVD are of interest in the semiconductor industry (see Semiconductors). [Pg.44]

Kuppers, D., and Lydtin, H. Preparation of Optical Waveguides with the Aid of Plasma-Activated Chemical Vapour Deposition at Low Pressures. 89, 107-131 (1980). [Pg.166]

A second important factor affecting the kidneys sensitivity to chemicals is its ability to concentrate the tubular fluid and, as a consequence, as water and salts are removed, to concentrate any chemicals it contains. Thus a nontoxic concentration in the plasma may be converted to one that is toxic in the tubular fluid. The transport characteristics of the renal tubules also contribute to the delivery of potentially toxic concentrations of chemicals to the cells. If a chemical is actively secreted from the blood into the tubular fluid, it will accumulate initially within the cells of the proximal tubule or, if it is reabsorbed from the tubular fluid, it will pass into the cells in relatively high concentration. [Pg.274]

Up to now three chemical vapor deposition (CVD) techniques have proved suitable for the preparation of high quality optical fibers the outside vapour phase oxidation (OVPO) process8, the modified CVD (MCVD) process9 and the plasma-activated CVD (PCVD) process10. The last mentioned process will be the main subject of this article. To give a better appreciation of the principles the alternative processes will be described briefly. [Pg.111]

This chapter gives an introduction into the preparation of optical fibers by means of the plasma-activated chemical vapour deposition (PCVD) method. [Pg.130]

Plasma-Activated Chemical Vapour Deposition at Low Pressures... [Pg.146]

Chemical modification is generally taken to mean a process involving the creation of a chemical bond (usually covalent) between a surface cell wall polymer and an introduced reagent to form a novel adduct. This can be done through several approaches, including plasma activation and graft polymerization with vinyl monomers, which are very well described in literature. The primary... [Pg.233]

The most conventional non-equilibrium plasma-chemical systems that produce diamond films use H2-CH4 mixture as a feed gas. Plasma activation of this mixture leads to the gas-phase formation of hydrogen atoms, methyl radicals (CH3), and acetylene (C2H2), which play a major role in further film growth. Transport of the gas-phase active species to the substrate is mostly provided by diffusion. The substrate is usually made from metal, silicon, or ceramics and is specially treated to create diamond nucleation centers. The temperature of the substrate is sustained at the level of 1000-1300 K to provide effective diamond synthesis. The synthesis of diamond films is provided by numerous elementary surface reactions. Four chemical reactions in particular describe the most general kinetic features of the process. First of all, surface recombination of atomic lydrogen from the gas phase into molecular hydrogen returns back to the gas phase ... [Pg.672]

Plasma cleaning Dry process (no solvents or chemical solutions) active oxygen plasma is an aggressive cleaner for organic residues effective in removing adhesive bleedout Electron-free plasma is required to avoid damage to sensitive components cleaning surfaces with plasma prior to adhesive cure enhances bleedout... [Pg.160]


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See also in sourсe #XX -- [ Pg.89 , Pg.107 , Pg.113 ]




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