The skutterudite compound CoSb3 exhibits excellent thermoelectric properties for thermoelectric application. The composition plays an important role in affecting the microstructural and thermoelectric behavior of CoSb3, especially in the form of thin film. In this study, the Co-excess and Sb-excess CoSb3 thin films were prepared by radio frequency and direct magnetron co-sputtering technique. It was found that the thin film with excess Co exhibits a significant n-type conduction behavior and transforms to p-type conduction behavior with Sb rich. The X-ray diffraction patterns show that either the Co-excess or Sb-excess samples contain skutterudite CoSb3 and a secondary phase CoSb2. Additionally, Sb can be found in the Sb-excess samples, yet no Co can be observed in the Co-excess samples. (C) 2017 Elsevier B.V. All rights reserved.