Thermoelectric Properties of Bi2Te3-Based Thin Films with Fine Grains Fabricated by Pulsed Laser Deposition

Abstract

Bi2Te3-based thin films were fabricated on quartz glass substrates by the pulsed laser deposition (PLD) method. By adjustment of the substrate temperature, films with c-axis orientation to the surface of the substrates were grown, and their in-plane electric resistivity and Seebeck coefficient were comparable with those of the bulk material. In contrast, their cross-plane thermal conductivity (evaluated using a thermoreflectance system with nanosecond pulsed laser heating) was comparatively much lower, possibly due to the grain size being as small as 40 nm (estimated based on X-ray diffraction measurement). The dimensionless figure of merit, ZT, for in-plane direction of n-type Bi2Te3 thin films was estimated based on the measurement results.