The influence of a Te-depleted surface on the thermoelectric transport properties of Bi 2 Te 3 nanowires

摘要: We report on thermoelectric transport measurements along the basal plane of several individual, single-crystalline Bi2Te3 nanowires (NWs) with different cross-sectional areas, grown by a vapor–liquid–solid method. Lithographically defined microdevices allowed us to determine Seebeck coefficient S, electrical conductivity σ, and thermal κ individual NWs. The NWs studied show near intrinsic properties low conductivities around σ = (3.2 ± 0.9) × 104 Ω−1 m−1 at room temperature. observe transition from positive negative values (S = +133 μVK−1 S = −87 μVK−1) increasing surface-to-volume ratio temperature, which can be explained presence an approximately 5 nm thick Te-depleted layer surface our are in range κ = (1.4 ± 0.4) Wm−1 K−1 is lower than literature for bulk Bi2Te3. attribute this suppression enhanced scattering phonons Despite their reduced conductivities, investigated only moderate figure merit between 0.02 0.18 due properties.