Nanowires complex structure

In a further extension of LCG growth, Lieber and coworkers and Yang and coworkers independently demonstrated the preparation of nanowires with structurally complex radial or axial heterostructures. Radial or core-shell heterostructure nanowires were formed by depositing layers on a core nanowire (Fig. 6A). Using this approach, homoepitaxial growth of B-doped Si shells on intrinsic Si and heteroepitaxial... 

Evaporation and deposition is a straightforward method to assembly nanoparticles as a thin coat by replicating surface features of templates. Evaporation and deposition can produce fine structures from bio-templates. Au microshells showing diatom frustule morphologies and complex structures at the nanoscale continuous Au nanowires as thin as lOnm can be formed on DNA by evap-... 

The Electrochemical Dip-Pen Nanolithography (E-DPN) leads to direct writing of PTh nanowires (diameter less than 100 nm) on ihe surface of semiconducting or insulating materials, thus allowing the fabrication of complex structures which are proposed for the design of devices with multipurpose applications (electronics, defense, pharmaceutics, and biotechnology) [171]. 

The fundamental physical properties of nanowire materials can be improved even more to surpass their bulk counterpart using precisely engineered NW heterostructures. It has been recently demonstrated that Si/Ge/Si core/shell nanowires exhibit electron mobility surpassing that of state-of-the-art technology.46 Group III-V nitride core/shell NWs of multiple layers of epitaxial structures with atomically sharp interfaces have also been demonstrated with well-controlled and tunable optical and electronic properties.47,48 Together, the studies demonstrate that semiconductor nanowires represent one of the best-defined nanoscale building block classes, with well-controlled chemical composition, physical size, and superior electronic/optical properties, and therefore, that they are ideally suited for assembly of more complex functional systems. 

Much attention is currently devoted to the synthesis and properties of shape-persistent macrocycles[l]. Such compounds are interesting for a variety of reasons including formation of columnar stacks potentially capable of performing as nanopores for incorporation into membranes or for the generation of nanowires[2]. Furthermore, in shape-persistent macrocycles incorporating coordination units, enc/o-cyclic metal-ion coordination may be exploited to generate nanowires[3], whereas e.ro-cyclic coordination can be used to construct large arrays of polynuclear metal complexes[4]. Shape-persistent macrocycles with reactive substituents may also be linked to other units to yield multicomponent, hierarchical structures. 

Up to now, most of our discussion featured small molecules, complexes, or clusters. In this section, we examine on how these conclusions could be extended to the realm of functional assemblies and nanomaterials. We begin with examining the structures and physical characteristics of carbon containing systems. We then progress to a discussion of organic nanotubes, metallic and encapsulated nanowires, and finally, nanodevices. 

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