Review of thermoelectric and galvanomagnetic transport in bismuth nanowires

J. P. Heremans

Delphi Research Labs, Delphi Corporation, 51786 Shelby Parkway, Shelby Township, MI 48315, USA

The experimental transport data measured on bismuth nanowires, 4 to 200 nm in diameter, imbedded in porous host materials such as alumina and silica, are reviewed here. We observe a very large enhancement of the thermoelectric power of bismuth nanowires with diameters on the order of 4 to 15 nm. Lin, Sun and Dresselhaus (Phys. Rev. B vol. 62, p 4610, 2000) had theoretically predicted such enhancement, and their paper suggests that it should lead to the development of high figure of merit thermoelectric materials. The thermopower is maximized when the wire diameter is 9 nm, presumably because localization effects begin to dominate at smaller diameters. The temperature dependence of the electrical resistance of these nanocomposite samples is also consistent with the theory, and is very different from that of bulk bismuth. Magnetoresistance data show evidence for localization effects when the wire diameter is smaller than 50 nm, and these effects become dominant below 10 nm. The transport properties of the bismuth nanowires will be compared to those of zinc and antimony nanowires of similar diameters, which remain metallic.