Index of content:
Volume 120, Issue 14, 14 October 2016
- SPECIAL TOPIC: CUTTING EDGE PHYSICS IN FUNCTIONAL MATERIALS
Electronic transport in thermoelectric skutterudite thin films studied by resistance noise spectroscopy120(2016); http://dx.doi.org/10.1063/1.4961703View Description Hide Description
Skutterudites CoSb3 are considered interesting candidates for thermoelectric applications, because the filling of guest atoms into the cage-like structure has the potential to improve its thermoelectric properties by an increased phonon scattering, which reduces the thermal conductivity. This, however, requires that a high electrical conductivity is maintained. In this study, we performed resistivity, Hall effect, and fluctuation spectroscopy measurements on polycrystalline thin films of semiconducting with . Our aim is to better understand the conventional dc electronic transport but also the low-frequency dynamical properties of the charge carriers. The electronic properties are highly sensitive to the filling factor z as well as other parameters, e.g., the Sb content. The resistivity can be described by Mott variable range hopping at low temperatures. A large 1/f noise level suggests an influence of the granularity of the polycrystalline thin films. By analyzing the 1/f-noise and two-level fluctuations, which are abundant for filled samples annealed at 500 °C, we are able to determine the energy distribution of the relevant electronic switching processes. A likely explanation for the observed low-frequency dynamics is capture/emission processes of impurities with a broad distribution within the energy gap.