Thermoelectric power of bismuth nanowires

Abstract

We report here measurements of the thermoelectric power and longitudinal magneto-Seebeck coefficient of 200 nm diameter single-crystal bismuth nanowires. Nanowires of pure Bi and of n-type-doped Bi (with Te at about $5\ifmmode\times\else\texttimes\fi{}{10}^{18}{\mathrm{cm}}^{\mathrm{\ensuremath{-}}3})$ were measured. The wires are imbedded in porous anodic alumina. The data are taken on arrays of wires connected in parallel, at temperatures from 8 to 300 K, and, between 10 and 80 K, in magnetic fields from 0 to 5 Tesla. It has been theoretically calculated that bismuth nanowires should have a strongly increased thermoelectric figure of merit over bulk Bi, when the diameter is decreased below about 10 nm. The nanowires in this study were selected because they are easier to prepare and handle. The temperature-dependent thermopower data are consistent with the partial electron and hole thermopower values calculated using the carrier Fermi energies obtained from Shubnikov--de Haas oscillations on the same samples.