Thermal Transport in Bismuth Nanowires

We report here the first measurements of the temperature dependence of the thermal conductance of a nanocomposite material made from 200 nm diameter single-crystal bismuth nanowires imbedded in an amorphous anodic alumina matrix. The thermoelectric power of the Bi nanowires is also reported. Nanowires prepared from pure Bi and from Bi n-type doped with Te to about 5x10 18 cm -3 were measured. Theoretical calculations show that nanowires of Bi should have an enhanced thermoelectric figure of merit. Bi quantum wires with diameters on the order of 7 nm have a calculated figure of merit ZT=2 at 300 K. The electrical resistance is similar to that reported in previous work. 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. The thermal conductance of the alumina/Bi composite follows a T n law with 1.2≤ n