Thermoelectric transport properties of single bismuth nanowires

We present a novel technique for measuring the power factor (Seebeck coefficient and resistivity) of a single isolated Bi nanowire. Electron beam lithography is used to pattern electrodes on top of a 40 nm diameter Bi nanowire along with a microscopic heater and thermocouples. Running current through the heater generates a temperature gradient of 0.5 K over a distance of 10 μm across the nanowire. Measurement of the Seebeck voltage of the nanowires was not possible due to the highly resistive and non-ohmic contacts. The non-linearity in the i(V) characteristics of the electrical contacts are understood by detailed modeling of the tunneling mechanism made through the electrical contacts. The prospect of using the poor contacts to perform tunneling spectroscopy of the electronic density of states of the nanowires is evaluated using this model.