Co-Sb is a new kind of promising thermoelectric material depending on its extremely high hole mobility, high thermoelectric power and relatively low thermal conductivity because of its complicated crystal structure. In order to obtain the best Co/Sb composition ratios, thin films with various Co/Sb composition ratios were obtained by ion beam sputtering technique with a fan-shaped target at room-temperature. The target was made by different Co and Sb plate’s areas. All the samples were annealed at 350 °C and 400 °C for one hour in vacuum chamber. The maximum Seebeck coefficient of the thin films was -210 μV/K when the thin film was annealed at 400 °C whose plate areas ratios of Co/Sb was 1:3. However the thin film possessing the maximum Seebeck coefficient has a large resistivity that causes the worse thermoelectric property. When plate ratio of Co/Sb is 1:4, the thin film had the maximum power factor of 1.56 mWm<sup>-1</sup>K<sup>-2</sup> with an moderate seebeck coefficient of -41 μV/K and an conductivity of 9.3×10<sup>5</sup> Sm<sup>-1</sup>.
Co-Sb based thermoelectric materials has been identified as a new promising thermoelectric material because of its extremely high hole mobility, high thermoelectric power, and relatively low thermal conductivity due to complexity in the crystal structure. In this work, Co-Sb based thin films were prepared by ion beam sputtering technique and the annealing process had been used to optimize the thermoelectric properties of the thin films. The results indicate that the thin films annealed at vacuum chamber with the chamber pressure of 6.0×10<sup>-4</sup> Pa has worse thermoelectric properties than the thin films annealed at Ar atmosphere. The thin film with single CoSb<sub>3</sub> phase which annealed at 400°C at Ar atmosphere has a maximum power factor of 1.8 mWm<sup>-1</sup>K<sup>-2</sup> with the Seebeck coefficient of 50 μV/K and the conductivity of 7×105 Sm<sup>-1</sup>. Also, the thermoelectric voltage of the thin film is stable through the testing temperature increases.