Electrical properties of a chemical sensor constructed from mats of GaN nanowires decorated with gold nanoparticles as a function of exposure to Ar, N2, and methane are presented. The Au nanoparticle decorated nanowires exhibited chemically selective electrical responses. The sensor exhibits a nominal response to Ar and slightly greater response for N2. Upon exposure to methane the conductivity is suppressed by 50% relative to vacuum. The effect is fully reversible and is independent of exposure history. We offer a model by which the change in the current is caused by a change in the depletion depth of the nanowires, the change in the depletion depth being due to an adsorbate induced change in the potential on the gold nanoparticles on the surface of the nanowires.
Articles you may be interested inEffect of Zn doping on SnAg solder microstructure and electromigration stability Experimental evaluation of wetting dynamics models for Sn 63 Pb 37 and SnAg 4.0 Cu 0.5 solder materials J. Appl. Phys.Massive spalling of intermetallic compounds in solder-substrate reactions due to limited supply of the active elementThe objective of this study is to synthesize and characterize different nanoporous structures by chemical etching. The experiments are conducted on three different materials. 6 carat white gold leafs ͑Au/ Ag alloy, 1:3 ratio by weight͒ are etched by nitric acid to obtain nanoporous gold structures. During etching, the gold materials congregate to form well connected network structure that is freestanding. The nanoporous gold samples have pore sizes from a few nanometers to a few hundred nanometers depending on the etching time. The second one is the 50/ 50 solder sheets ͑Pb/ Sn alloy͒ in which tin is etched by sulfuric acid to create nanostructured lead material. The third is Imitation Italian gold leafs ͑Cu/ Zn alloy, 82/ 18 by wt %͒ in which zinc is etched by sodium hydroxide solution to produce nanostructured copper materials. These porous materials are analyzed by scanning electron microscopy and energy dispersive x-ray spectroscopy. The authors observe the composition of the porous materials at every stage of chemical dealloying and conduct experiments with different process parameters to obtain various sizes of self-ordered porous structures. The authors have fabricated nanoporous gold films with pore sizes of 10-100 nm, nanostructured lead materials with pore sizes of 100-300 nm, and copper nanostructures with pore sizes of 10-150 nm. The results demonstrate that chemical etching is a simple and effective fabrication technique for nanoporous materials with high surface area and well defined pore morphology.
We have developed a novel technique to fabricate extremely uniform arrays of nano-sized dots. Regular arrays of nanometer-sized metallic dots are obtianed by magnetron sputtering deposition through a nanochannel glass replica mask. The platinum replica masks are fabricated using thin film deposition on an etched nanochannel glass and contain hexagonally patterned uniform voids with diameters as small as 50 nanometers. The metallic dot density can be as high as 5×1011 per square centimeter. The magnetic properties of Ni and Co dot arrays have been studied by a Alternating Gradient Magnetometer. The magnetic dot array can be used as pinning centers for superconductors and also can be used as the discrete magnetic media for magnetic recording.
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