Thin film multilayer systems observation

Table 2.4. Binary metal/metal systems observed to exhibit solid-state amorphiz-ation by interdiffusion or other type of driven mixing (e.g. mechanical codeformation). The table lists the type of experiment, the typical reaction temperature, TR (for the case of interdiffusion reaction) and references. (B thin-film bilayer diffusion couples, M thin-film multilayer diffusion couple, S interdiffusion of polycrystalline layer of one component with single crystal of another component, MA mechanical alloying of the metals, MAT thermal reaction of a mechanically deformed composite...

To reconcile experimental and theoretical observations on the size and temperature dependences of the elastic and plastic deformation of nanoscopic systems including atomic chains, NTs, liquid and solid skins, thin films, multilayers, nanocavities, nanograins, and nanocomposites to provide with consistent understanding. 

At low overpotentials nucleation of the Ni deposit starts at the elbows of the reconstruction (Fig. 4(b)), followed by anisotropic growth of monolayer islands perpendictilar to the double rows of the reconstruction (Fig. 4(c)). For multilayer coverages a layer-by-layer growth of the Ni thin film was observed up to thicknesses of six layers. Under UHV conditions, this system exhibits a similar nucleation behavior but the subsequent growth proceeds isotropically and in a more three-dimensional fashion [27]. Both in UHV and in file electrochemical environment the nucleation of islands is preceded by the formation of dqiressions at the elbows. This indicates that Au surface atoms at these sites are replaced by Ni atoms, which subsequently act as centers for adlayer island nucleation [28]. Ihis demonstrates r-reaching mechanistic similarities for deposition at the metal-vacuum and the metal-electrolyte interface, even in complex cases. 

As already mentioned, the stresses in thin films may present problems in many industrial applications of the films. Early observations of thin films in optical applications showed that particularly when the film thickness was large, cracks arose, which had cloudy marks and sometimes the films even became detached from the substrate. Exact measurements of evaporated single films and film systems indicated a partial stress compensation, especially in dielectric multilayers, since low refractive films often have tensile stresses, whilst high refractive films have compressive stresses [157,158]. 

Figure 29. For the latter case, it is considered that the semiconducting re-electron systems are separated by insulating hydrocarbon spacers, resulting in alternate thin layers of organic semiconductor and insulator in these monolayer assemblies. The direct current - voltage (I - V) characteristics were mea- sured for the multilayers H2Pc(R)8 and Cu-Pc(R)8 in directions perpendicular and parallel to the film plane. In both cases, the linear I - V relationships of Ohm s law were observed at low electric field and obtained DC conductivities are summarized in Table 3. The normal conductivity (ajJ were ca. 10 13 S cm-1, while the lateral ones p//) were 3.4 x 10-7 and 9.9 x 10 7 S cm 1 for films of the metal-free and copper Pc derivatives, respectively. The former (ojJ tended to decrease slightly with increase of Figure 29. Schematical illustration of the substituent alkyl chain length,...

Electron-Induced Reactions—HREELS Measurements. Novel LEE-induced chemistry has also been observed in HREEL measurements of molecular solids and molecules physisorbed on the surface of RGS. For example, Lepage et ah, building on the initial observations of Jay-Gerin et al. [141], have employed HREELS to measure in situ, neutral dissociation products arising from the impact of low-energy electrons on thin multilayer films of methanol [37] and acetone [38]. The technique is similar to that developed earlier by Martel et al. [258] for chemisorbed systems, in that the same electron beam is used for both the production and the detection of the neutral fragments. However, in the work of Lepage... 

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