Nanowires anodic alumina templates

Figure 6(a) shows a SEM image of bismuth nanowires embedded in an anodic alumina template after pressure injection. The pore diameter of the template was about 42 nm, and the maximum pressure and temperature applied for the injection process were about 310 bar and 325°C, respectively. A small amount of copper was introduced into hquid bismuth to enhance its injection the copper atoms should be segregated from bismuth during solidification because they have zero solubihty in solid bismuth. Upon solidification, the copper flakes were brought to the top surface of Bi due to their... 

Fig. 6. (a) SEM image of the bottom surface of an anodic alumina template filled with bismuth. The pore diameter is 42 nm. (b) TEM micrograph of the cross section of a 65-nm bismuth nanowire array (Zhang et al., 1999). 

The smallest diameter attained for bismuth nanowires by the pressure injection method was about 13 nm, using a pressure of approximately 0.3 kbar (Zhang et al., 1999). Finer nanowires might be fabricated by increasing injection pressures (Huber et al., 2000), but it remains to be seen if the anodic alumina templates would retain their structural integrity under those high pressures. 

Multisegment CdTe-Au-CdTe nanowires have also been used for FET-based sensing of DNA [53], Synthesized by consecutive electrodeposition onto an anodized alumina template these metal-semiconductor nanowires exhibit a p-type behavior. Thiol-terminated ssDNA probes were bound via Au-thiol interaction to the Au segment of the nanowires. Target DNA could be detected at 1 fiM and higher concentrations. 

Fig. 30. Branched copper nanowires. Inset branched nano-chaimels of an etched anodic alumina template, showing copper deposits formed in situ.

Wang, Y.C., Leu, I.C. Hon, M.H. (2004). Dielectric property and structure of anodic alumina template and their effects on the electrophoretic deposition characteristics of ZnO nanowire arrays, /. Appl. Phys. Vol. 95, ppl444-1449. 

Wu, Jeremy R, Brown, Ian W.M., Kemmitt, Tim, Bowden, Mark E. (2010a) Hierarchical Anodic Alumina Template-assisted Fabrication of Nanowires. Proc. of International Conference on Nanoscience and Nanotechnology (ICONN), 2010. Page(s) 29 - 32 DOI 10.1109/ICONN.2010.6045163. Publ. lEEEXplore. 

Fig. 1 Examples of morphologies of semiconductor nanostructures, (a) metal assisted Si etching and formation of Si-NWs. Electrochemical formation of (b) microporous silicon, (c) ZnO nanorods, (d) porous CdSe using porous alumina template, (e) CdTe nanowires using alumina template, (1) CdS nanowires using alumina template, (g) mesoporous Xi02 film using doctor blade method, (h) self-ordered anodic Xi02 nanotubes and (i) cross section image of the same Xi02 nanotubes (reproduced with permission from Ref. 8,27,28,45 8).

An exhaustive study has been carried out recently on the synthesis of BN nanotubes and nanowires by various CVD techniques.17 The methods examined include heating boric acid with activated carbon, multi-walled carbon nanotubes, catalytic iron particles or a mixture of activated carbon and iron particles, in the presence of ammonia. With activated carbon, BN nanowires are obtained as the primary product. However, with multi-walled carbon tubes, high yields of pure BN nanotubes are obtained as the major product. BN nanotubes with different structures were obtained on heating boric acid and iron particles in the presence of NH3. Aligned BN nanotubes are obtained when aligned multi-walled nanotubes are used as the templates (Fig. 40). Prior to this report, alignment of BN nanotubes was achieved by the synthesis of the BN nanotubule composites in the pores of the anodic alumina oxide, by the decomposition of 2,4,6-trichloroborazine at 750 °C.116 Attempts had been made earlier to align BN nanotubes by... 

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