Cross-plane thermal conductivity of highly oriented nanocrystalline bismuth antimony telluride thin films

The cross-plane thermal conductivity of highly oriented nanocrystalline bismuth antimony telluride thin films is investigated. The thin film was deposited by a flash evaporation method. The resulting film was oriented with the c-axis to the substrate, and was composed of fine grains with an average grain size of 150 nm. The cross-plane thermal conductivity of the film was measured by a 3ω method at room temperature, and was determined to be 0.6 W m−1 K−1. Compared to the single crystal bulk alloy of nearly the same composition and carrier concentration, the thin film exhibited a 20% reduction in the thermal conductivity.