[Show abstract][Hide abstract] ABSTRACT: Lithographically patterned nanowire electrodeposition (LPNE) is a new method for fabricating polycrystalline metal nanowires using electrodeposition. In LPNE, a sacrificial metal (M(1)=silver or nickel) layer, 5-100 nm in thickness, is first vapor deposited onto a glass, oxidized silicon, or Kapton polymer film. A (+) photoresist (PR) layer is then deposited, photopatterned, and the exposed Ag or Ni is removed by wet etching. The etching duration is adjusted to produce an undercut approximately 300 nm in width at the edges of the exposed PR. This undercut produces a horizontal trench with a precisely defined height equal to the thickness of the M(1) layer. Within this trench, a nanowire of metal M(2) is electrodeposited (M(2)=gold, platinum, palladium, or bismuth). Finally the PR layer and M(1) layer are removed. The nanowire height and width can be independently controlled down to minimum dimensions of 5 nm (h) and 11 nm (w), for example, in the case of platinum. These nanowires can be 1 cm in total length. We measure the temperature-dependent resistance of 100 microm sections of Au and Pd wires in order to estimate an electrical grain size for comparison with measurements by X-ray diffraction and transmission electron microscopy. Nanowire arrays can be postpatterned to produce two-dimensional arrays of nanorods. Nanowire patterns can also be overlaid one on top of another by repeating the LPNE process twice in succession to produce, for example, arrays of low-impedance, nanowire-nanowire junctions.
[Show abstract][Hide abstract] ABSTRACT: A fabrication method to prepare Pb(core)/ZnO(shell) nanostructures and its application for high-sensitivity nanothermometer, has demonstrated. The facile galvanic displacement method was used to prepare high sensitive solid-state Pb(core)/ZnO(shell) nanothermometers. The galvanic displacement method was used for its minimum equipment requirement, high throughput, and environmental friendly nature. The method also used Transmission electron microscopy (TEM) to determine the thermal expansion properties of solid Pb inside the nanocables in real time. Zn foil with Pb(NO3)2 solution was used to fabricate the Pb/ZnO nanocables at room temperature. The Pb/ZnO system can be suitable for nanothermometers for operating in the solid state. It was observed during the study that the ZnO and Pb chemical interactions can cause the cycling of temperature and thermometer degradation.
[Show abstract][Hide abstract] 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; DOI:10.1039/b815603d · 6.83 Impact Factor
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