Alternative deposition techniques

Basically two alternative activation techniques have been reported to deposit tungsten other than by thermal activation. These are activation by aid of a gas discharge (plasma enhanced or PECVD) or by optical activation (photo -mostly laser- enhanced or LCVD). The advantage of these techniques is that the substrate temperature can be relatively low which might be of importance for future developments. In the next two sections we will discuss both PECVD and LCVD. 

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Pulsed field gel electrophoresis, 9 746 Pulsed flashlamps, 14 619 Pulsed laser deposition chamber, 24 739 Pulsed laser deposition (PLD), 24 738-743 advancement of, 24 739 as an alternative deposition technique, 24 742-743... 

Carbon Composites. In this class of materials, carbon or graphite fibers are embedded in a carbon or graphite matrix. The matrix can be formed by two methods chemical vapor deposition (CVD) and coking. In the case of chemical vapor deposition (see Film deposition techniques) a hydrocarbon gas is introduced into a reaction chamber in which carbon formed from the decomposition of the gas condenses on the surface of carbon fibers. An alternative method is to mold a carbon fiber—resin mixture into shape and coke the resin precursor at high temperatures and then foUow with CVD. In both methods the process has to be repeated until a desired density is obtained. 

Molten bath deposition The interchange reaction also takes place when the coating metal halide is dissolved in a fused salt. Alternatively, deposition may be by electrolysis. Another technique uses the coating metal dissolved in molten calcium ... 

Vitreous enamel is normally applied to the prepared metal or over a ground-coat by spraying or dipping. Alternative wet techniques are used, of which the most common has been electrostatic wet spraying. Electrophoretic deposition from the slurry has been found to be highly suitable for some components. 

In order to achieve the enhanced strength, atomically sharp A IB interfaces are needed for the mechanism proposed by Koehler. The multilayer hlms should be deposited under a relative low temperature in order to avoid the interdiffusion between the layers. Thus, PVD techniques such as evaporation and sputtering deposition are the reasonable methods to fabricate multilayer hlms. There are several ways to achieve the alternate deposition of the composing layers A and hxed substrate position mode, repeated substrate po-... 

Ion layer gas reaction (ILGAR) is an alternative sequential chemical deposition technique for which a metal-containing precursor solution is first transferred to the substrate by dipping (dip-ILGAR) or spraying (spray-ILGAR)... 

Although the sputter deposition technique can provide a cheap and directly controlled deposition method, the performance of PEM fuel cells with sputtered CLs is still inferior to that of conventional ink-based fuel cells. In addition, other issues arise related to the physical properties of sputtered catalyst layers, such as low lateral electrical conductivity of the thin metallic films [96,108]. Furthermore, the smaller particle size of sputter-deposited Ft can hinder water transport because of the high resistance to water transport in a thick, dense, sputtered Ft layer [108]. Currently, the sputter deposition method is not considered an economically viable alternative for large-scale electrode fabrication [82] and further research is underway to improve methods. 

While the carbon arc method yields products in amounts that are easily characterized, there is a number of caveats of which one must be aware. Since the carbon arc operates at extremely high temperatures (>2000 °C) and emits copious amounts of light, there is the very real possibility of pyrolysis and/or photolysis of both substrate and products. These problems may be minimized by carrying out control experiments in which pyrolysis and photolysis products are identified and excluded. Maximum yields in carbon arc reactions are obtained when carbon and substrate are cocondensed. However, this technique can result in pyrolysis of substrate, which can be avoided by alternately depositing substrate and carbon on the cold reactor walls. Often both methods are employed in order to identify pyrolysis products. Since the carbon arc results in removal of macroscopic pieces of graphite from the rods, it is impossible to measure product yields based on actual carbon evaporated. 

Evaporative decomposition erf solutions and spary pyrolysis have been found to be useful in the preparation of submicrometer oxide and non-oxide particles, including high temperature superconducting ceramics [819, 820], Allowing uniform aerosol droplets (titanium ethoxide in ethanol, for example) to react with a vapor (water, for example) to produce spherical colloidal particles with controllable sizes and size distributions [821-825] is an alternative vapor phase approach. Chemical vapor deposition techniques (CVD) have also been extended to the formation of ceramic particles [825]. 

Watanabe et al. [Ill] have used an electrostatic layer - by - layer deposition technique to fabricate self - assembled films from alternating molecular layers of oppositely charged PAMAM dendrimers and low molar mass compounds. 

For enzyme attachment to the silicon microreactor tested, a layer-by-layer technique was employed to build a multilayer system of polyions and enzyme. Deposition of multilayers was accomplished by alternating positively and negatively charged layers of polydimethyldiallyl ammonium chloride (PDDA) and polystyrene sulfonate (PSS), respectively, to which was attached urease enzyme. After depositing in succession three layers of PDDA, PSS, and PDDA, three layers of urease enzyme were alternately deposited with three layers of PDDA. The resulting architecture is described as follows ... 

The device may be formed by depositing alternating layers of cadmium telluride and mercury telluride by vapour phase deposition techniques and interdiffuse the layers, either during growth or subsequently, so as to form a mercury cadmium telluride layer. Reference is made to GB-A-2146663 (The Secretary of State for Defence, GB, 24.04.85) and GB-A-2203757 (Philips Electronic and Associated Industries Limited, GB, 26.10.88). 

NCs is indispensable. In the case of cadmium chalcogenide NCs, the concentration of a colloidal solution can be determined in good approximation by means of UV-vis absorption spectroscopy thanks to tabulated relationships between the excitonic peak, the NC size, and the molar absorption coefficient.96 An advanced approach for shell growth derived from chemical bath deposition techniques and aiming at the precise control of the shell thickness is the so-called SILAR (successive ion layer adsorption and reaction) method.97 It is based on the formation of one monolayer at a time by alternating the injections of cationic and anionic precursors and has been applied first for the synthesis of CdSe/CdS CS NCs. Monodispersity of the samples was maintained for CdS shell thicknesses of up to five monolayers on 3.5 nm core CdSe NCs, as reflected by the narrow PL linewidths obtained in the range of 23 to 26 nm FWHM. 

Wurtzite-structure ZnO thin films grown by a variety of deposition techniques, as well as commercially available single crystal bulk samples are discussed. Furthermore, data for ZnO thin films intermixed with numerous elements are reviewed. Most of the results are obtained by SE, which is a precise and reliable tool for measurements of the DFs. The SE results are supplemented by Raman scattering and electrical Hall-effect measurement data, as well as data reported in the literature by similar or alternative techniques (reflection, transmission, and luminescence excitation spectroscopy). 

A promising alternative is surface textured doped zinc oxide films. ZnO films can offer excellent transparency and are highly resistant to hydrogen plasmas [78]. Textured ZnO films have been prepared by several deposition techniques. Examples are boron doped zinc oxide (ZnO B) prepared by low-pressure chemical vapor deposition (LPCVD) ([79,80], see also Chap. 6) or ZnO films deposited by expanding thermal plasma CVD [81], Quite recently, ZnO films for back contacts of solar modules have been developed using chemical bath deposition [82]. 

Layer-by-layer (LBL) deposition has become one of the major techniques to fabricate multilayer films. It was introduced by Decher in the form of alternate deposition of cationic and anionic polyelectrolytes [56-58]. This so-called electrostatic self-assembly process dominates the research in this area. However, more recently alternative driving forces have been employed, such as hydrogen bonding, coordination bonding, charge-transfer interactions, and covalent bonding. Since this review concerns the formation, functionaliza-... 

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