Aluminum deposition parameters

Table 8.2 The influence of different process parameters on the nanostructure of aluminum deposits. In the case of additive addition benzoic acid was used.

Some important deposition parameters to control ZnO Al film properties are deposition pressure, substrate temperature, and amount of oxygen in the sputter gas mixture (see e.g. [93,96,100,101]). Doping concentration in ZnO films plays another important role for opto-electronic properties [97,100,102]. Figure 8.13 shows the spectral transmission of films that were reactively sputtered from targets with different aluminum concentration at optimized conditions [93]. Sputter conditions and film properties are given in Table 8.2. 

In this paragraph we will examine first the adhesion properties and the structure of aluminum films evaporated i) on oi-axially oriented polymer and ii) on treated (corona and fluorine) polymer samples. Then, an analysis of the influence of some parameters of the metallization such as the thickness of the aluminum film, the evaporation angle and the aluminum deposition by sputtering, will be presented. 

Figure 9.10 Discharge parameter of CH4 glow discharge the amount of aluminum deposited is determined by XPS.

Aluminum alloys with chromium The electrodeposition of Cr has been investigated in acidic chloroaluminates by Ali et al. [27]. They report that the Cr content in the AlCr deposit can vary from 0 to 94 mol%, depending on the deposition parameters. The deposit consists both of Cr-rich and Al-rich solid solutions as well as intermetaUic compounds. An interesting feature of these deposits is their high-temperature oxidation resistance the layers seem to withstand temperatures up to 800 °C, so that coatings with such an alloy could be interesting for applications in engines. 

A main advantage of electrochemical deposition is the ease of manipulation by deposition parameters, such as potential, time, concentration of monomers, and water content in the deposition solution. Many works have shown that the thickness and properties of sol-gel films are strongly dependent on the deposition conditions [2,18,21,36]. Specifically, nanostructured sol-gel films can be electro-deposited using a template as a building block. The templates used include an anodized aluminum oxide (AAO) membrane and a cetyltrimethylammonium bromide (CTAB) surfectant [28,37]. In addition, the electrodeposition of sol-gel films can also be spatially confined to conductive patterns on the electrode surface [38], or localized by a microelectrode using scanning electrochemical microscopy (SECM) [39,40]. 

The use of aluminum-based masks in photolithography has been proposed.347 According to the scheme employed, aluminum is deposited onto a polished glass sheet. The regions of the mask that should be light transparent are then converted into porous oxide. As the operation of aluminum anodization exhibits a much better vertical anisotropy than chemical etching, the masks obtained reproduce the parameters of standard masks more precisely than the chromium masks usually used. 

Bulk Ag-Al alloys, containing up to 12 a/o Al, were electrodeposited from melt containing benzene as a co-solvent. Examination by x-ray diffraction (XRD) indicated that the low-Al deposits were single-phase fee Ag solid solutions whereas those approaching 12 a/o were two-phase, fee Ag and hep i>-Ag2Al. The composition at which ti-Ag2Al first nucleates was not determined. The maximum solubility of aluminum in fee silver is about 20.4 a/o at 450 °C [20] and is reduced to about 7 a/o at room temperature. One would expect the lattice parameter of the fee phase to decrease only slightly when aluminum alloys substitutionally with silver because the... 

The third contribution is particularly devoted to the concept of so-called single source precursors (SSPs). SSPs contain all the atoms of the different elements necessary for the deposition of the desired material in one single molecule. One motivation for using this concept is to simplify the accompanying gas-phase reactions and thus reduce the process parameters to be controlled and optimised. However, SSPs may offer a unique chance of depositing metastable materials that cannot be derived by other methods. M. Veith and S. Mathur provide such an example in their paper entitled Single-Source-Precursor CVD Alkoxy and Siloxy Aluminum Hydrides . 

Mo are single phase, supersaturated solid solutions having an fee structure very similar to that of pure Al. Broad reflection indicative of an amorphous phase appears in deposits containing more than 6.5 atom% Mo. As the Mo content of the deposits is increased, the amount of fee phase in the alloy decreases whereas that of the amorphous phase increases. When the Mo content is more than 10 atom%, the deposits are completely amorphous. As the Mo atom has a smaller lattice volume than Al, the lattice parameter for the deposits decreases with increasing Mo content. Potentiodynamic anodic polarization experiments in deaerated aqueous NaCl revealed that increasing the Mo content for the Al-Mo alloy increases the pitting potential. It appears that the Al-Mo deposits show better corrosion resistance than most other aluminum-transition metal alloys prepared from chloroaluminate ionic liquids. 

A question must be raised as to why the tap water and the calcium bicarbonate washing treatments give such different results. The alkaline pH of the tap water suggests that calcium carbonate or bicarbonate is present and that the final product deposited in the fiber should be similar to that obtained with the pure bicarbonate solution. However, the chemical makeup of any city tap water is very complex and must contain a number of components that could affect the stability of cellulose. For example, the municipal treatment plant in Ottawa adds large amounts of alum (aluminum sulfate) to the water to settle particulate matter. Because alum makes the water very acidic, lime is then added to raise the pH. The result is that a large amount of calcium sulfate is present in the tap water and must affect the overall chemistry of the salts deposited in the fibers. One may further speculate that the anions present can influence the stability of cellulose as much as the cations. Any comprehensive understanding of the factors involved must include aH parameters. 

The rate of sputtering of aluminum from the electrode used in a magnetron plasma polymerization system is dependent on the plasma energy density, which can be stipulated by the external parameter Vjp, which is the acceleration potential in the vicinity of the cathode, for Ar discharge, while the deposition of CH4 is dependent on WjFM in joules per kilogram of CH4 for LCVD as described in Chapter 8. 

Figure 9.9 Sputtering on the discharge parameter W/p the aluminum sputtering is measured by the deposition onto the thickness monitor sensor in the glow discharge of argon, flow rate (cm sTP /min) , 2.3 O, 5.6 A, 12.4 A, 23.3. Adapted from Ref. 15.

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... 

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