12 research outputs found
Diameter-dependent thermopower of Bi nanowires
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 150-480 nm, have been carried out over a wide range of
temperatures (4-300 K) and magnetic fields (0-14 T). We find that the
thermopower of intrinsic Bi wires in this diameter range is positive (type-p)
below about 150 K, displaying a peak at around 40 K. In comparison, intrinsic
bulk Bi is type-n. Magneto-thermopower 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-hole scattering.Comment: 32 pages, 12 figures. Previous version replaced to improve
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