In the last two decades numerous novel nanoscale materials have been synthesized. Electronic characterization is essential for the integration of these materials into current semiconductor devices. The investigation of thermoelectric transport properties of novel materials provides not only an understanding of their effectiveness in energy conversion applications but also insight into their electronic structure. We will present our investigations of the thermoelectric transport properties of semiconducting ZnO and Si nanowires (NWs), phase changing antimony telluride (Sb2Te3) NWs, single layer graphene and single walled carbon nanotubes. Since it is often difficult to measure the carrier density of nanowires using a Hall bar geometry, we will present a method to acquire the carrier density through the measurement of the temperature dependence of the thermoelectric power (TEP) in semiconducting NWs. Graphene and carbon nanotubes exhibit both positive and negative values of TEP, with a peak value on the order of kB/e at room temperature. At high magnetic fields in the quantum Hall regime in graphene, the TEP exhibits characteristic oscillations similar to those found in 2-dimensional electron gases. We explore thermoelectric effects in the presence of Fabry-Perot interference at low temperatures in carbon nanotubes. We analyze the validity of the semiclassical description of transport in these low dimensional carbon materials by comparing the measured TEP to that predicted by the Mott relation.
|Subjects||Condensed matter physics; Materials science|
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