Mechanically-exfoliated stacks of thin films of Bi2Te3 topological insulators with enhanced thermoelectric performance

The authors report on graphene-like mechanical exfoliation of single-crystal Bi2Te3 films and thermoelectric characterization of the stacks of such films. Thermal conductivity of the resulting pseudosuperlattices was measured by the hot disk and laser flash techniques. The room temperature in-plane (cross-plane) thermal conductivity of the stacks decreases by a factor of similar to 2.4 (3.5) as compared to bulk. The thermal conductivity reduction with preserved electrical properties leads to strong increase in the thermoelectric figure of merit. It is suggested that the film thinning to few-quintuples and tuning of the Fermi level can help in achieving the topological-insulator surface transport regime with an extraordinary thermoelectric efficiency. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3494529]