Metallic nanowires growth

Pena DJ, Mbindyo JKN, Carado AJ, Mallouk TE, Keating CD, Razavi B, Mayer TS (2002) Template growth of photoconductive metal-CdSe-metal nanowires. J Phys Chem B 106 7458-7462... 

Solution-Liquid-Solid (SLS) growth of semiconductor nanowires by Wang etal. (2006). The synthesis proceeds by a solution-based catalysed growth mechanism in which nanometer-scale metallic droplets catalyse the decomposition of metallo-organic precursors and crystalline nanowire growth. 

Enzymes functionalized with metallic NPs were used as biocatalytic hybrids for the growth of metallic nanowires. The catalytic enlargement of metal nanoparticles by products generated by different enzymes was used to develop different optical sensors that follow the activities of enzymes and analyze their substrates.57 For example, hydrogen peroxide generated by the biocatalyzed oxidation of glucose by O2 in the... 

The synthesis of conductive metallic nanowires that bridged two microelectrodes separated by a gap of 12-16 im was demonstrated by the growth of a silver nanowire on a DNA template that bridged the gap (Fig. 12.26).92 Short thiolated nucleic acids (12 bases long) were attached to the microelectrodes, and these acted as sticky ends for the hybridization of /.-DNA that bridged the gap. The association of Ag+ to the phosphate groups of the template, followed by their reduction with hydroquinone under basic conditions, resulted in the formation of Ag° nanoclusters on the DNA template. The subsequent enlargement of the Ag° seeds by the catalytic reduction of Ag+ by hydroquinone, under acidic conditions, yielded continuous Ag nanowires with a width of ca. lOOnm. The nanowires revealed nonlinear I—V... 

Recently, the VLS growth method has been extended beyond the gas-phase reaction to synthesis of Si nanowires in Si-containing solvent (Holmes et al, 2000). In this case 2.5-nm Au nanocrystals were dispersed in supercritical hexane with a silicon precursor (e.g., diphenylsilane) under a pressure of 200-270 bar at 500°C, at which temperature the diphenylsilane decomposes to Si atoms. The Au nanocrystals serve as seeds for the Si nanowire growth, because they form an alloy with Si, which is in equilibrium with pure Si. It is suggested that the Si atoms would dissolve in the Au crystals until the saturation point is reached then they are expelled from the particle to form a nanowire with a diameter similar to the catalyst particle. This method has an advantage over the laser-ablated Si nanowire in that the nanowire diameter can be well controlled by the Au particle size, whereas liquid metal droplets produced by the laser ablation process tend to exhibit a much broader size distribution. With this approach, highly crystalline Si nanowires with diameters ranging from 4 nm to 5 nm have been produced by Holmes et al. (2000). The crystal orientation of these Si nanowires can be controlled by the reaction pressure. 

Fabrication or InP/InAs/InP core-multishell heterostructure nanowire arrays shown in Fig. 24 has been achieved by selective area metal-organic vapour phase epitaxy.1 These core-multishell nanowires were designed to accommodate a strained InAs quantum well layer in a higher band gap InP nanowire. Precise control over the nanowire growth direction and the heterojunction formation enabled the successful fabrication of the nanostructure in which all the three layers were epitaxially grown without the assistance of a catalyst. 

The seeds are then added to a growth solution that consists of fresh metal salt, and a surfactant, cetyltrimethylammonium bromide, CTAB, that directs the growth of nanopartides into nanorods and nanowires. Growth is initiated by the addition... 

In early VLS whisker growth studies, there was no attempt to control the liquid alloy droplet size. Consequently, whisker diameters were large, ranging from 100 nm to 0.2 mm. The smallest whisker diameters that could be produced were limited by the minimum stable liquid droplet diameter ( 100 nm). In 2000, researchers began to apply size-selected nanometer-size colloidal metal particles as seeds to promote semiconductor nanowire growth. 

Fig. 4.11 SEM images of metal nanowires, (a) Copper nanowires. These nanowires were electrodeposited from the solution, using E =-S00 and E =-5 The growth times employed in each experiment were 1-120,...

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