  Semiconductor quantum wires constitute a promising thermoelectric material
because of the increase of the electronic density of states in low-dimensional
materials. We studied the magnetic-field-dependent resistance and Seebeck
coefficient of a high-density network of 6-nm-diameter wires of Bi and of
Bi(1-x)Te(x), x=0.0014, in porous Vycor glass. The resistance R increases as
temperature decreases from 300 K down to 0.3 K for both composites. However, in
contrast to recent results that demonstrate the semiconducting behavior of the
resistance and very large enhancements of the thermoelectric power of
composites containing Bi nanowires with diameters of 9 and 15 nm, we find that
the resistance is not thermally activated and that the thermoelectric power of
the composites is of the same order of magnitude as the thermoelectric power of
bulk Bi. Our results are consistent with the nanowires having carrier density
that is enhanced by surface effects.
