We present a study of electronic transport in individual Bi nanowires of large diameter relative to the Fermi wavelength. Measurements of the resistance and thermopower of intrinsic and Sn-doped Bi wires with various wire diameters, ranging from $150\text{to}480\mathrm{nm}$, have been carried out over a wide range of temperatures $(4–300\mathrm{K})$ and magnetic fields $(0–14\mathrm{T})$. We find that the thermopower of intrinsic Bi wires in this diameter range is positive (type $p$) below about $150\mathrm{K}$, displaying a peak at around $40\mathrm{K}$. In comparison, intrinsic bulk Bi is type $n$. Magnetothermopower effects due to the decrease of surface scattering when the cyclotron diameter is less than the wire diameter are demonstrated. The measurements are interpreted in terms of a model of diffusive thermopower, where the mobility limitations posed by hole-boundary scattering are much less severe than those due to electron-boundary scattering.

• Received 7 July 2007

DOI:https://doi.org/10.1103/PhysRevB.77.035422