Design of Apparatus for Ni/Mg2Si and Ni/MnSi1.75 Contact Resistance Determination for Thermoelectric Legs

In recent decades, thermoelectricity has been widely studied as a potential new source of renewable energy. One of the major challenges to improve the efficiency of thermoelectric (TE) devices is to minimize the contact resistance between the active material and the electrodes, since this represents the major loss of charge in a TE module. This article describes the fabrication of an apparatus for TE leg characterization built with commercial and custom-made parts based on the analog one-dimensional transmission-line method. This device permits contact resistance measurements of bulk TE legs. p- and n-type TE materials, Mg2Si0.98Bi0.02 and MnSi1.75Ge0.02, respectively, were metallized with nickel foils and used as test materials for contact resistance characterization. Contact resistance values of 0.5 m Omega mm(2) for Ni/Mg2Si0.98Bi0.02 junctions and 4 m Omega mm(2) for Ni/MnSi1.75Ge0.02 junctions have been measured. Contact resistance measurements are discussed depending on materials processing and the experimental measurement conditions.