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The Nanofabrication of Quantum Wires for the Next Generation of Thermoelectrics
Published online by Cambridge University Press: 10 February 2011
Abstract
The fabrication of a thermoelectric nanocomposite material consisting of nanometer scale bismuth (Bi) wires embedded in a porous mica template host is discussed in detail. In fabricating the mica templates, a positive ion accelerator is employed to irradiate 10 μm thick mica sheets with collimated beams of 15 MeV carbon ions at fluence levels of 1.5 × 1013 ions/cm2. The normally incident beam generates latent nuclear damage tracks in the direction oriented perpendicularly to the mica basal plane. Atomic Force Microscope (AFM) pictures of etched tracks verify that we have fabricated porous templates containing arrays of channels with densities up to 1013/cm2 and diameters as small as 5 nanometers, thus providing pores having an aspect ratio of about 2000:1. Scanning electron micrographs of 50 nm diameter tracks show that these are parallel channels with smooth, non-tapered walls. In addition, to fabricate the wires we have developed a solution-electrodeposition process employing a PC processor-driven potentiostatic/galvanostatic system. Currently, we are electrochemically embedding 10 μm long Bi wires through the nanochannel templates. The potentiostatic electrodeposition behavior of these wires is described. Current-voltage waveforms confirm that the wires are electrically uninterrupted through the mica template. Transmission electron micrographs (TEM) show these wires are single crystals, of well-defined orientation with diameters down to 50 Å. We observe bundles of 80 Å wires with a packing density of about 109/cm2. Energy Dispersive X-ray Spectroscopy (EDS) has corroborated the presence of Bi in the nanochannels. The observation of the bismuth crystal orientation in the porous mica template is examined.
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- Copyright © Materials Research Society 1999
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