Effect of nanostructuration on the thermal conductivity of thermoelectric materials

We have investigated various kinds of nanowires (Si, Bi₂Te₃, SiGe) in order to evaluate the influence of the nanostructuration on their thermal conductivity. The method used is a 3ω-SThM (Scanning Thermal Microscopy) technique which enables to simultaneously measure the topography and the thermal conductivity on an assembly of NWs. We detail the procedure from the measurement itself to the nanowire thermal conductivity estimation. We show that the nanostructuration leads to a thermal conductivity reduction for the 3 materials we have studied and that Si and SiGe nanowire samples seem more promising than Bi₂Te₃ NWs in terms of thermoelectric applications.