Block copolymer mediated deposition of metal nanoparticles on germanium nanowires.
Department of Chemistry, and National Institute for Nanotechnology, University of Alberta, Edmonton, AB, Canada.Chemical Communications (Impact Factor: 6.38). 04/2007; DOI: 10.1039/b616883c
ABSTRACT Galvanic displacement, mediated by a diblock copolymer, leads to deposition of well dispersed gold and silver nanoparticles on germanium nanowires.
- Advanced Materials 01/2008; 20(24):4789-4792. · 14.83 Impact Factor
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ABSTRACT: The diffraction limit, d approximately lambda/2, constrains the resolution with which structures may be produced using photolithography. Practical limits for d are in the 100 nm range. To circumvent this limit, photolithography can be used to fabricate a sacrificial electrode that is then used to initiate and propagate the growth by electrodeposition of a nanowire. We have described a version of this strategy in which the sacrificial electrode delimits one edge of the nascent nanowire, and a microfabricated "ceiling" constrains its height during growth. The width of the nanowire is determined by the electrochemical deposition parameters (deposition time, applied potential, and solution composition). Using this method, called lithographically patterned nanowire electrodeposition (LPNE), nanowires with minimum dimensions of 11 nm (w) x 5 nm (h) have been obtained. The lengths of these nanowires can be wafer-scale. LPNE has been used to synthesize nanowires composed of bismuth, gold, silver, palladium, platinum, and lead telluride.Chemical Communications 03/2009; · 6.38 Impact Factor
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ABSTRACT: This work focuses on the synthesis and interfacial characterization of gold nanostructures on silicon surfaces, including Si(111), Si(100), and Si nanowires. The synthetic approach uses galvanic displacement, a type of electroless deposition that takes place in an efficient manner under aqueous, room-temperature conditions. The case of gold-on-silicon has been widely studied and used for several applications and yet, a number of important, fundamental questions remain as to the nature of the interface. Some studies are suggestive of heteroepitaxial growth of gold on the silicon surface, whereas others point to the existence of a silicon-gold intermetallic sandwiched between the metallic gold and the underlying silicon substrate. Through detailed high resolution transmission electron microscopy (TEM), combined with selected area electron diffraction (SAED) and nanobeam diffraction (NBD), heteroepitaxial gold that is grown by galvanic displacement is confirmed on both Si(100) and Si(111), as well as silicon nanowires. The coincident site lattice (CSL) of gold-on-silicon results in a very small 0.2% lattice mismatch due to the coincidence of four gold lattices to three of silicon. The presence of gold-silicon intermetallics is suggested by the appearance of additional spots in the electron diffraction data. The gold-silicon interfaces appear heterogeneous with distinct areas of heteroepitaxial gold on silicon, and others, less well-defined, where intermetallics may reside. The high resolution cross-sectional TEM images reveal a roughened silicon interface under these aqueous galvanic displacement conditions, which most likely promotes nucleation of metallic gold islands that merge over time: a Volmer-Weber growth mechanism in the initial stages.ACS Nano 09/2009; 3(9):2809-17. · 12.03 Impact Factor
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