Optimization in fabricating skutterudite CoSb3 thermoelectric thin films

CoSb3 based thin films were prepared at room temperature by radio-frequency sputtering and the CoSb3 alloy targets were used with the Co:Sb atomic ratio of 1:3, 1:3.5 and 1:4, respectively. Then the as-deposited thin films were annealed at 300 and 325 °C under argon atmosphere for 1 h. It can be found that the thin films have single skutterudite phase structure when used the Co:Sb (1:3.5) alloy target. Though other films show the primary CoSb3 phase structure, there are some impurity phases can be observed from the X-ray diffraction patterns. For contrast, the thin films prepared by the Co:Sb (1:3.5) alloy target were annealed from 250 to 350 °C with the temperature interval of 25 °C. The results show that the thin film annealed at 325 °C has the best thermoelectric performance.