  We present measurements of Shubnikov-de Haas oscillations in arrays of
bismuth nanowires with diameters comparable to the Fermi wavelength. For 80-nm
wires the hole concentration is less than 30% of that for bulk Bi, consistent
with current models of quantum confinement effects. However, 30-nm wires
nanowires which are predicted to be a semiconducting show a nearly isotropic
short period of 0.025 T-1, consistent with a heavy carrier concentration five
times that of bulk Bi. These results are discussed in terms of surface-induced
charge carriers in a spherical Fermi surface pocket that are uniformly
distributed in the 30-nm nanowire volume and that inhibit the
semimetal-to-semiconductor transition.
