Improved thermoelectric performance of highly-oriented nanocrystalline bismuth antimony telluride thin films is described The thin films are deposited by a flash evaporation method followed by annealing in hydrogen By optimizing the annealing conditions the resulting thin films exhibit almost perfect orientation with the c-axis normal to the substrate and are composed of nano-sized grains with an average grain size of 150 nm The in-plane electrical conductivity and Seebeck coefficient were measured at room temperature The cross-plane thermal conductivity of the thin films was measured by a 3 omega method and the in-plane thermal conductivity was evaluated by using an anisotropic factor of thermal conductivity based on a single crystal bulk alloy with almost the same composition and carrier concentration The measured cross-plane thermal conductivity is 0 56 W/(m K) and the in-plane thermal conductivity is evaluated to be 1 05 W/(m K) Finally the In-plane power factor and figure-of-merit ZT of the thin films are 35 6 mu W/(cm K(2)) and 1 0 at 300 K respectively (C) 2010 Elsevier B V All rights reserved