A novel method to extract contact resistivity for thermoelectric semiconductor.

Contact electrical resistance is a critical issue to be addressed in thermoelectric modules. A commercial instrument in thermoelectricity is demonstrated for the first time to extract the contact resistivity of thermoelectric legs by use of the three options of the probe distance. The specimen comprises two legs of bismuth telluride that are connected with reflow soldering. The probe distances are calibrated with a homogeneous sample of constantan. The linear fittings between the electrical resistance and the probe gap are employed in the calibration and in deriving the contact resistivity. The contact resistivity of n-type Bi2Te3 and p-type Bi2Te3 with nickel plating to the Sn64Bi35Ag1 solder is determined to be 17.4 µΩ cm2 and 9.8 µΩ cm2 at ambient temperature, respectively. The contact resistivities at two other temperatures are extracted as well so that the contact resistivity as a function of temperature would be available from the proposed method.