Multilayer deposition process

K. Y. K. Man, H. L. Wong, W. K. Chan, C. Y. Kwong, A. B. Djurisic, Efficient photodetectors fabricated from a metal-containing conjugated polymer by a multilayer deposition process, Chemistry of Materials 2004, 16, 365. 

The use of UPD layers can in principle generate deposits with composition modulated on the atomic scale, and Pauling et al. have produced what they call hetero-structured ultra-thin films containing Ag, Pd and T1 by this method [158], Stickney and coworkers have assembled multilayered deposits of CdTe and GaAs by addition of one atomic layer of the individual components at a time, a process they call electrochemical atomic-layer epitaxy [159 162], The essential controlling feature in the UPD mechanism is that the deposited layers are allowed to reach equilibrium. Hence, the process represents an extreme of local, reversible control. 

The final film thicknesses were increased either by increasing the deposition time or by multilayer deposition. Although the film thickness increases with longer deposition time, the film morphology tends to be poor, as shown in Fig. 7.9. A two-layer technique that used two layers of TBSBCCO films, with an intermediate layer of Ag, improved the film uniformity and morphology, as shown in Fig. 7.10. The deposition process for the multiple layer is as follows (1) Single-crystal substrates are coated with 300 A of Ag (2) TBSBCCO films (0.4-1.3 pm) are prepared by electrodeposition (ED) on Ag/LAO (3) 300 A of Ag are deposited on ED-TBSBCCO/Ag/LAO (4) the second layer of TBSBCCO is electrodeposited (0.4-1.3 pm) on Ag/ED-TBSBCCO/Ag/LAO and (5) the complete two-layer system is reacted. 

Another solution proposed for the low-temperature deposit process for fluorhy-droxyapatite onto porous zirconia bone scaffold was reported by Kim et al. [161], It is based on the immersion of the scaffold in a slurry of dispersed HA-FA powders in polyvinylbutyl for several hours, followed by drying and subsequent heat treatments at 800°C and 1200°C for binder (polyvinylbutyl) burnout. The process can be repeated fora multilayer film deposit. 

Traditionally, monolayer and multilayer adsorption have been used in detergency, mineral processing, flotation, stability of food and pharmaceutical emulsions, and the like, and, as a consequence, the topics of this chapter have been a central part of colloid science. In recent years, however, research on monolayer and multilayer deposition has mushroomed rapidly because of significant new opportunities. 

FIGURE 4. (a) Structures of PPVG and PEDOT PSS. (b) The fabricating of the polyelectrolyte-organometallic multilayer film by the layer-by-layer deposition process. 

The deposition of ZnO coatings by in-line sputtering is basically a multilayer approach since the film grows under strongly varying conditions. The analysis of static deposition experiments in terms of particle flux and film property distribution is, therefore, helpful to understand and hence to improve the deposition process. 

Electrochemical deposition of lithium usually forms a fresh Li surface which is exposed to the solution phase. The newly formed surface reacts immediately with the solution species and thus becomes covered by surface films composed of reduction products of solution species. In any event, the surface films that cover these electrodes have a multilayer structure [49], resulting from a delicate balance among several types of possible reduction processes of solution species, dissolution-deposition cycles of surface species, and secondary reactions between surface species and solution components, as explained above. Consequently, the microscopic surface film structure may be mosaiclike, containing different regions of surface species. The structure and composition of these surface films determine the morphology of Li dissolution-deposition processes and, thus, the performance of Li electrodes as battery anodes. Due to the mosaic structure of the surface... 

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