High-Output-Power Densities From Molecular Beam Epitaxy Grown N- And P-Type Pbtese-Based Thermoelectrics Via Improved Contact Metallization

Electrical power densities of up to 33 W/cm(2) and up to 12 W/cm(2) were obtained for n-type and p-type PbTeSe-based stand-alone thermoelectric devices, respectively, at modest temperature gradients of similar to 200 degrees C (T-cold = 25 degrees C). These large power densities were enabled by greatly improving electrical contact resistivities in the thermoelectric devices. Electrical contacts with contact resistivities as low as 3.9 x 10(-6) Omega cm(2) and 4.0 x 10(-6) Omega cm(2) for n- and p-type telluride-based- materials, respectively, were developed by investigating several metallization schemes and contact layer doping/alloy combinations, in conjunction with a novel contact application process. This process exposes heated semiconductor surfaces to an atomic hydrogen flux under high vacuum for surface cleaning (oxide and carbon removal), followed immediately by an in-situ electron-beam evaporation of the metal layers. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4712425]