Effects of chemical intermixing on electrical and thermal contact conductances at metallized bismuth and antimony telluride interfaces

Tailoring electrical and thermal contact conductivities (Sigma(c) and Gamma(c)) across metallized pnictogen chalcogenide interfaces is key for realizing efficient thermoelectric devices. The authors report that Cu, Ni, Ti, and Ta diffusion and interfacial telluride formation with n-Bi2Te3 and p-Sb2Te3 influence both Sigma(c) and Gamma(c). Cu metallization yields the highest Gamma(c) and the lowest Sigma(c), correlating with maximal metal diffusion and copper telluride formation. Ni diffuses less and yields the highest Sigma(c) with Sb2Te3 due to p-type nickel telluride formation, which diminishes Sigma(c) improvement with n-Bi2Te3 interfaces. Ta and Ti contacts yield the lowest properties similar to that in Ni-metallized structures. These correlations between interfacial diffusion and phase formation on electronic and thermal transport properties will be important for devising suitable metallization for thermoelectric devices. (C) 2015 American Vacuum Society.