Vapor deposition of aluminum

Dannetun P, Boman M, Stafstrom S, Salaneck WR, Lazzaroni R, Fredriksson C, Bredas JL, Zamboni R, Taliani C (1993) The chemical and electronic structure of the interface between aluminum and polythiophene semiconductors. J Chem Phys 99(l) 664-672 Ahn H, Whitten JE (2003) Vapor-deposition of aluminum on thiophene-terminated self-assembled monolayers on gold. J Phys Chem B 107(27) 6565-6572 Fisher GL, Flooper A, Opila RL, Jung DR, Allara DL, Winograd N (1999) The interaction between vapor-deposited A1 atoms and methylester-terminated self-assembled monolayers studied by time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy and infrared reflectance spectroscopy. J Electron Spectrosc Relat Phenom 98-99 139-148... 

Lu P, Demirkan K, Opila RL, Walker AV (2008) Room-temperature chemical vapor deposition of aluminum and aluminum oxides on alkanethiolate self-assembled monolayers. J Phys Chem C 112(6) 2091-2098... 

Altogether easier of access, more stable, and more tractable are complexes in which AIH3 is coordinated by one or more base molecules, e.g., (MegNl AlHs (n = 1 or 2). These are of interest as hydride sources for hydroalumination of unsaturated substrates 10, 140), as precursors to the hydrides of other metals, and, as already noted, in the chemical vapor deposition of aluminum metal in thin-film technology (21-26). The 1 1 trimethylamine adduct, MesN-AlHs, is monomeric in the vapor but, in common with PhCH2Me2N-AlH3 and... 

Ion vapor deposition of aluminum is attractive because it avoids the environmental and toxicological problems associated with cadmium. It does not cause hydrogen embrittlement of steel or solid metal embrittlement of steel or titanium, and it should be more galvanically compatible with aluminum alloy structure and avoid the exfoliation corrosion of sensitive alumimun alloy structme. However, views on the ability of alumimun to protect steel fasteners appear to vary. A view is that the presently available pure aluminum coatings are not able to provide adequate sacrificial protection to steel in a chloride ion environment, and for this reason a recommendation is made for the development of alruninrun coatings containing small amounts of zinc or other elements for improved protection. 

B.T. Nevill, Ion vapor deposition of aluminum an alternative to cadmium. Plat. Surf. 

Boron filaments are formed by the chemical vapor deposition of boron trichloride on tungsten wire. High performance reinforcing boron fibers are available from 10—20 mm in diameter. These are used mainly in epoxy resins and aluminum and titanium. Commercial uses include golf club shafts, tennis and squash racquets, and fishing rods. The primary use is in the aerospace industry. 

Recently, the efficacy of LDHs as catalyst precursors for the synthesis of carbon nanotubes via catalytic chemical vapor deposition of acetylene has been reported by Duan et al. [72]. Nanometer-sized cobalt particles were prepared by calcination and subsequent reduction of a single LDH precursor containing cobalt(II) and aluminum ions homogeneously dispersed at the atomic level. Multi-walled carbon nanotubes with uniform diameters were obtained. 

Depending on purposes, a plastic film under the vapor-deposited C is dissolved away with a solvent. By this method, a very thin C support-film of smaller than lOnm in thickness can be made easily. An aluminum (Al) support-film can be made similarly, by vapor-deposition of Al onto a plastic film put on a grid and then by dissolving away the plastic film. The reflection rings from the Al support-film can be used as an internal reference to calibrate the camera length of SAED pattern, and this support film does give no amorphous halo. When an ultra-thin C support-film (less than 5nm in thickness) is desired, a microgrid (MG see Section 3.1.2) should be used on which an ultra-thin film made by indirect vapor-deposition of C has been put in advance. 

Aluminum spraying is used to coat less corrosion-resistant alloys. In the case of some composites, corrosion is due to the galvanic action between the aluminum matrix and the reinforcing material. Aluminum thermal spraying has been successfully used for the protection of the discontinous silicon carbide/aluminum composites, and continuous graphite/aluminum. Other protection procedures include sulfuric acid anodizing and iron vapor deposition on aluminum.44... 

Yamada-Takamura, Y. et al.. Hydrogen permeation barrier performance characterization of vapor deposited amorphous aluminum oxide films using coloration of tungsten oxide. Surface and Coatings Technology, 153, 114 (2002). 

For the selective liquid phase alkylation of naphthalene with propene to form 2,6-diisopropylnaphthalene, mordenite again seems to be the most promising catalyst [42]. However, while this zeolite shows a high selectivity for 13-substitution of naphthalene, its activity is low compared to faujasites [43, 44]. Chemical vapor deposition, variation of the aluminum content and of the solvent are methods used to improve the catalytic behavior of mordenite catalysts in this reaction. Chemical vapor deposition of silicon or zirconium alkoxides were claimed to improve the I3,l3 -selectivity of zeolite Beta in this reaction [45]. A recurrent matter of dispute are the parameters influencing the yield ratio of 2,6- and 2,7-diisopropylnaphthalene. Both molecules are presumed to have the same molecular dimensions. With regard to the formation of 2,6-diisopropylnaphthalene, alkylation with isopropylbromide... 

Matheson Gas Products) was used as the carrier gas. Substrates were prepared by vapor deposition of an opaque layer of aluminum on glass microscope slides. Polymer film thicknesses were determined by measuring the step height between a masked and unmasked portion of the specimen with a Rank, Taylor, and Hobson Talystep 1 traversing stylus. Deposited films were stored in a vacuum dessicator prior to measurement of the infrared spectra in order to minimize the absorption of moisture from the atmosphere. 

In contrast to titania and niobia, alumina is a support that does not display the classic SMSI behavior outlined above, at least for practical catalysts (173, 175). Bischke et al. (176) studied CO methanation over model Ni/Al203 catalysts prepared by evaporation of Al onto a W foil, subsequent oxidation of the Al, and finally vapor deposition of Ni onto the thin A1203 film. Specific reaction rates (per Ni surface atom) and the activation energy were similar to those found for pure Ni crystals and practical Ni/Al203 catalysts. This agrees with the classical picture of A1203 as a more or less inert support for this catalyst and the known structural insensitivity of this reaction over Ni (see above). Submonolayer quantities of oxidized aluminum were shown by Levin et al. (186) to only decrease the rate of methanation over a Rh foil, in proportion to the fraction of Rh sites covered by the oxide film. 

Several techniques have been developed to deposit alumina films on different surfaces such as those of semiconductors or metals. These films find apphcation in various areas. In most cases, amorphous alumina films are desired. Depending on the deposition techniques, various precursors may be used the following combinations have been reported plasma-enhanced atomic layer deposition using trimethylaluminum (112), metal-organic chemical vapor deposition using aluminum tri-iso-propoxide (113), and condensation from the gas phase using laser-evaporated alumina (114). Similar evaporation techniques can also be apphed to prepare Y-AI2O3 powders (115,116). 

FIGURE 13 Examples of kinetic processes classified by types of phases involved, (a) Gas-gas reaction equilibrium between hydrogen gas, iodine gas, and hydrogen iodide gas. (f>) Gas-Uquid evaporation of liquid water from a glass, (c) Liquid-Liquid gradual separation of an oil-water mixture, (d) Gas-solid chemical vapor deposition of a thin Si film, (e) Liquid-solid corrosion of Cu metal in seawater, (f) Solid-solid precipitation of CuAlj particles from a copper-aluminum alloy during a heat treatment process. 

Klein TM, Niu D, Epling WS et al. (1999) Evidence of aluminum silicate formation during chemical vapor deposition of amorphous AI2O3 thin films on Si(lOO). Appl Phys Lett... 

Shieh, J., Hon, M.H., 2002. Plasma-enhanced chemical-vapor deposition of titanium aluminum carbonitride/amorphous-carbon nanocomposite thin films. Journal of Vacuum Science Technology A 20 (1), 87—92. 

Parasitie reaetions also oeeur in eleetronie device fabrieation. Thus, in chemical vapor deposition of AlAs one ean use A1(CH3)3 (trimethyl aluminum) or A1(C2H5)3 (triethyl aluminum) as the souree gas for Al. The triethyl eompound reacts with... 

Metallization layers are generally deposited either by CVD or by physical vapor deposition methods such as evaporation (qv) or sputtering. In recent years sputter deposition has become the predominant technique for aluminum metallization. Energetic ions are used to bombard a target such as soHd aluminum to release atoms that subsequentiy condense on the desired substrate surface. The quaUty of the deposited layers depends on the cleanliness and efficiency of the vacuum systems used in the process. The mass deposited per unit area can be calculated using the cosine law of deposition ... 

The first is a pyrolytic approach in which the heat dehvered by the laser breaks chemical bonds in vapor-phase reactants above the surface, allowing deposition of the reaction products only in the small heated area. The second is a direct photolytic breakup of a vapor-phase reactant. This approach requires a laser with proper wavelength to initiate the photochemical reaction. Often ultraviolet excimer lasers have been used. One example is the breakup of trimethyl aluminum [75-24-1] gas using an ultraviolet laser to produce free aluminum [7429-90-5], which deposits on the surface. Again, the deposition is only on the localized area which the beam strikes. 

Another important function of metallic coatings is to provide wear resistance. Hard chromium, electroless nickel, composites of nickel and diamond, or diffusion or vapor-phase deposits of sUicon carbide [409-21-2], SiC , SiC tungsten carbide [56780-56-4], WC and boron carbide [12069-32-8], B4C, are examples. Chemical resistance at high temperatures is provided by aUoys of aluminum and platinum [7440-06-4] or other precious metals (10—14). 

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