Measurements of Bi2Te3 nanowire thermal conductivity and Seebeck coefficient

Theoretical predictions suggest that the thermoelectric properties of nanowires could be greatly enhanced compared with the bulk materials. To investigate these predictions, bismuth telluride nanowires are synthesized by electrodeposition into the cavities of porous alumina templates. Individual nanowires are then isolated, and subjected to measurements of both thermal conductivity and Seebeck coefficient over temperatures ranging from 20 K to 320 K. All measurements are made using a microfabricated device consisting of two suspended membranes with integrated heaters and resistance thermometers. Platinum or carbon films are locally deposited at the wire and the heater pad junctions to enhance the contact conductance. Results show that the thermal conductivity of the measured Bi₂Te₃ nanowires varies from wire to wire and show different temperature dependence, probably because the wire composition and crystal structure are not the same.