Influence of semiconductor thickness for the contact resistance measurement with transfer length method at the interface between bismuth telluride thermoelectric materials and metals

The precise measurement and minimization of contact resistance (Rc) between the thermoelectric semiconductor and electrode are required for enhancing the conversion efficiency and reliability of thermoelectric generation (TEG) devices. The Rc values are obtained using the conventional transfer length method (TLM); however, the effect of semiconductor thickness on contact resistance remains unexplored. To gain a clearer understanding of this effect, this study fabricated samples with different semiconductor thicknesses and evaluated the specific contact resistivity (ρc) at the bismuth telluride (Bi2Te3)/barrier metals (Ti, Cr, and Ni) interfaces, regardless of the semiconductor dimension and device shape. Our TLM measurements revealed that the ρc of the Bi2Te3/barrier metals interfaces increased in the order of Ti, Cr, Ni. This study provides accurate data regarding the physical interface properties between Bi2Te3/barrier metals, enhancing the conversion performance and reliability of TEG devices.