Self templated substrates

Poly(ferrocenylsilane) polyions are readily processed to novel, fully organometallic multilayer thin films. Furthermore, these organometaUic polyions, featuring a hydrophobic backbone, enable one to make use of both electrostatic and hydrophobic interactions to fabricate self-organized patterns on templated substrates, with potential applications as aqueous pro-cessable ultrathin etch resists. 

The formation of nanostructures such as nanodot arrays has drawn a great attention due to the feasible applications in a variety of functional structures and nanodevices containing optoelectronic device, information storage, and sensing media [1-3]. The various methods such as self-assembled nanodots from solution onto substrate, strain-induced growth, and template-based methods have been proposed for the fabrication of nanodot arrays on a large area, [4-6]. However, most of these works can be applied to the small scale systems due to the limited material systems. 

The formation of bottom-up block copolymer patterns within or on top-down substrate patterns is the basis for so-called templated self-assembly processes, in which long-range order and orientation of microdomain patterns can be imposed by a template or guide . These top-down templates can take a variety of forms including periodic thickness profiles and chemically patterned surfaces. 

The original system is based on peptides that contain heptad repeats, where the first and fourth positions of the repeat are hydrophobic amino acids. Such sequences form a-helices, which assemble into coiled-coil structures, as represented in Figure 7.10. The principle is then the same as that used for von Kiedrowski s self-replicating nucleotides (von Kiedrowski 1986), in the sense that a full-length peptide template (having in this case 32-35 residues) directs the condensation of the two half-length peptide substrates. 

Finally, Majda has investigated a novel inorganic membrane-modified electrode [32]. The membrane used was a microporous alumina prepared by anodizing metallic aluminum in an acidic electrolyte [33]. Majda et al. lined the pores of these membranes with polymers and self-assembled monolayers and studied electron and ion transfer down the modified pore walls to a substrate electrode surface [32]. Martin and his coworkers have used the pores in such membranes as templates to prepare nanoscopic metal, polymer, and semiconductor particles [34],... 

The SERS spectra from an organic analyte deposited on the substrate were found to show a enhancement factor of 104, which is comparable to the enhancement obtained from two-dimensional silver gratings produced by electron beam lithography by Kahl et al. [39]. Like the self-assembled three-dimensional opal gratings, the templated gratings provide clear practical advantages over ordered substrates produced by more complex and expensive methods. The results reported are summarized in Table 10.2. From the... 

The last example we would like to discuss is a lattice of holes formed in stoichiometric hexagonal (h) BN double layers on Rh(lll), see Fig. 5(c) and [99]. The lattice is composed of holes in the BN-bilayer with a diameter of 24 2 A, and an average distance of 32 2 A. The holes in the upper layer are offset with respect to the smaller holes in the lower layer. We note that well-ordered superstructures with a large period have already been observed some time ago by means of LEED for borazine adsorption onto Re(0001) [102], while borazine adsorption onto other close-packed metal surfaces, such as Pt(lll), Pd(lll), and Ni(lll), leads to the self-limiting growth of commensurate ABN monolayers [103,104]. For BN/Rh(lll) it is not clear at present whether the Rh(lll) substrate is exposed at the bottom of the holes. If this was the case the surface would not only be periodic in morphology but also in chemistry, and therefore would constitute a very useful template for the growth of ordered superlattices of metals, semiconductors, and molecules. 

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