Investigation of low resistance contacts to Pb-Sb-Ag-Te (LAST) materials for module fabrication

Low electrical contact resistance is essential for the fabrication of high efficiency thermoelectric generators. These contacts must be stable to high temperatures and through thermal cycling. Here we present the fabrication procedure and characterization of several contacts to Pb-Sb-Ag-Te (LAST) compounds. Contact materials investigated include tungsten, antimony, tin, nickel, and a bismuth antimony based solder. The contacts were typically deposited by an electron beam evaporation method after careful preparation of the sample surface. The resistances were measured by using the transmission line model (TLM), and ohmic behavior was verified through current vs. voltage measurements. The best contact resistivities of less than 20 mu Omega(.)cm(2) 2 have been measured for annealed antimony to n-type LAST samples. We present these procedures for fabricating low resistance contacts and the use of these contact materials toward the fabrication of high efficiency thermoelectric generator modules.