Bismuth Telluride and Antimony Telluride Based Co-Evaporated Thermoelectric Thin Films

1. Bismuth Telluride and Antimony Telluride Based Co-Evaporated Thermoelectric Thin Films Daniel C. Ralph, Cornell University, ECCS 0335765 Solid-state thermoelectric generators are useful for energy harvesting in many microsystems such as implantable devices and sensor network applications. Thermoelectric (TE) materials are capable of directly converting a temperature difference to electrical energy and vice versa. Bismuth/antimony telluride compounds are the best room-temperature TE materials that can be fabricated as n/p-type thin films. High-quality TE thin films with good adhesion and uniformity are needed on a variety of substrates in order to provide design flexibility for thermoelectric microsystems. However, for each substrate optimization is needed of film adhesion, stress, and co-evaporation conditions for high-TE figure of merits, namely the substrate temperature (Tsub) and flux ratio. Here we study the effect of substrate on TE thin film electrical and thermal properties, morphology, crystal structure, grain size, surface roughness and composition. SEM and AFM images showing top surface of bismuth telluride (left) and antimony telluride (right) thermoelectric thin films co-evaporated at different substrate temperatures on oxide. • Niloufar Ghafouri, Rebecca L. Peterson, Ctirad Uherand Khalil Najafi, University of Michigan • Work performed in part at the Lurie Nanofabrication Facility