Deposition and Fabrication of Sputtered Bismuth Telluride and Antimony Telluride for Microscale Thermoelectric Energy Harvesters

Thermoelectric (TE) n-type bismuth telluride (Bi2Te3) films and p-type antimony telluride (Sb2Te3) films are grown on SiO2/Si substrates via radio frequency magnetron sputtering. The crystal structures and TE properties are characterized for 1 mu m and 10 mu m films deposited using different deposition conditions and using various heat treatment conditions. Single-target sputtered deposition of n-type Bi2Te3 films resulted in a Te-deficient off stoichiometric films due to the evaporation of tellurium. Two-target co-sputtered deposition using Bi2Te3 and Te targets at room temperature and subsequent anneal at 250 degrees C yielded a 10 mu m n-type film with -102 mu V/K for the Seebeck coefficient and 0.7 mW/K-2.m for the power factor. Similarly, prepared p-type Sb2Te3 film but using a single sputtering target yielded +110 mu V/K and 1.3 mW/K-2.m for their Seebeck coefficient and power factor respectively. The fabrication of the micro-scale thermoelectric energy generator (mu TEG) using separate n-type and p-type wafers is demonstrated.