Thermoelectric properties of skutterudite CoSb_3 thin films

摘要

The thermoelectric properties of Co-Sb thin films with different Sb content and with a thickness of 30 nm were investigated with respect to the composition and the corresponding structural properties of these films. The films were prepared by molecular beam deposition either by codeposition on heated substrates or room temperature deposition followed by a post-annealing step. It was found that the prepared films exhibit bipolar conduction, indicated by a positive Hall constant and a negative Seebeck coefficient. The obtained results can be well explained by using the bipolar model, assuming heavy electrons and light holes, which was finally confirmed experimentally by the preparation of p- and n-type doped CoSb_3 thin films. Furthermore, variable range hopping was identified by temperature dependent transport measurements as dominant conduction mechanism at low temperatures.