Thermoelectric properties of Bi and Bi/sub 2/Te/sub 3/ composites

Structure of Bismuth Telluride Nanowire Arrays Fabricated by Electrodeposition into Porous Anodic Alumina Templates

“…It is clear from these images that melting and recrystallization of the wires resulted in a grain structure that is very similar to the as-deposited structure with small, bamboo-type grains. A polycrystalline grain structure was also reported for ∼200 nm wires produced by pressure injection, where the average grain size was determined to be ∼40 nm using Scherrer's equation to evaluate the peak width in XRD spectra . Although the experimental control of a temperature gradient to achieve single crystals is well-established for larger structures (for example zone-melting in semiconductor growth), this approach is more difficult for dimensionally restricted structures such as the templates employed in this work (thickness ∼50 μm).…”

“…Bulk Bi 2 Te 3 has a high thermoelectric figure-of-merit and is widely used in commercial applications. Superlattices of Bi 2 Te 3 /Sb 2 Te 3 have recently been shown to have an enhanced thermoelectric figure-of-merit relative to bulk Bi 2 Te 3, and theoretical studies suggest that 1D structures (nanowires) may have an even higher figure-of-merit. − In previous work, both ∼200 nm − and ∼40 nm 9 diameter nanowire arrays have been fabricated by deposition of Bi 2 Te 3 into porous anodic alumina templates. These templates have good characteristics for nanowire array fabrication because they are thermally and mechanically stable and can be produced with a high density of high-aspect-ratio, parallel, nearly uniform pores with diameters ranging from ∼10 nm to several hundred nanometers. − Although a variety of methods have been reported for depositing Bi 2 Te 3 , − we have chosen electrodeposition because it enables good control over stoichiometry, can be used to deposit high-aspect-ratio structures, and results in electrically continuous wires.…”