Polycrystalline randomly oriented substrate

Electrodeposition on a randomly oriented polycrystalline substrate can result in the development of preferred orientation, or texture, in thicker deposits. In a polycrys-talline material, the crystallographic axis of individual grains (individual crystallites) that constitute the material are randomly oriented with respect to the axes of a fixed reference system (Fig. 33a). If one or more 

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Figure 7.15. Schematic representation of polycrystalline randomly oriented substrate (a) and substrate with preferred orientation (texture) (h).

The structure of a polycrystalline electrode depends on its preparation. Usually toe rough electrodes are prepared by electrochemical deposition of a given metal onto a suitable substrate. Microcrystals present in polycrystaUine samples are randomly oriented on the surface. Most likely, not only basal but also higher MiUer-index planes should be considered in anticipating toe final structure of the electrode surface. It was shown that the stmcture of the platinized platinum surface depends strongly on toe platinization conditions, e.g., on toe concentration of the platinization... 

The samples studied in this section are zirconia films deposited on sapphire substrates. These films are produced by using a sol-gel method based on a dipping process which we have already described. After drying the sample and firing it at a low-temperature, we get a polycrystalline film comprised of randomly oriented nanocrystals (see section 7.2.1). A high temperature process, in this case, lasting one hour at 1,500°C, would yield a set of epitaxial islands of zirconia (see sectiorts... 

One final procedure for minimizing substrate Raman scattering interference in thin polycrystalline films deposited on silica is based upon the polarization properties of the scattered light (16). Inherent molecular disorder present in vitreous silica substrates results in marked polarization anisotropy of the Raman-scattered light from the substrate. Raman scattering from a deposited polycrystalline film is isotropic since the individual randomly-oriented grains act to scramble the... 

With gold, as with other metal substrates, the relevant surface can be either polycrystalline, that is, composed of crystallites of random orientation, or single crystalline, that is, comprising one crystal plane of a well-defined and uniform orientation. In certain cases, a metal surface can be... 

Polysilicon is an aggregation of pure silicon crystals with random orientation deposited on the top of silicon substrate (see Figure 10.4). Polycrystalline silicon is deposited during... 

PS-PMMA system (Figure 9.6). The alignment field (30V/pm), produced by metal electrodes above and below the polymer film, acts like a parallel-plate capacitor with a micrometer-scale separation. While this technique is very successful in aligning cylinders perpendicular to the substrate, the field has little or no effect on the packing of the cylinders. A plan view of these structures reveals a polycrystalline lattice-like structure where each grain adopts a random orientation. Furthermore, these researchers have used lithography techniques to erode away PMMA cylinders and back fill with various metals, such as Co... 

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