Film deposition and annealing treatment of sputtered bismuth telluride based thin films

Abstract

In an effort to fabricate thin film thermoelectric generators, we prepared p-type antimony telluride and n-type bismuth telluride thin films by using a RF magnetron sputtering, after which a thermal annealing was implemented. We investigated the relationship between the annealing temperatures and the properties of both types of the thin films. The structural properties were analyzed by x-ray diffraction patterns and scanning electron microscope. The in-plane electrical properties, which were the electrical conductivity, Seebeck coefficient and power factor, were estimated at room temperature. As a result, the surface morphology of both types of the thin films exhibited nano-sized pores as the annealing temperature increased possibly because of the evaporation of tellurium atoms. This evaporation also induced to increase the defect density of both types of the thin films, and to be degraded their electrical properties. Therefore, we resulted in the higher thermoelectric properties at the annealing temperature of 300 °C; antimony telluride:  S 2 = 18.8  W/(cm ∙ K 2 ) and bismuth telluride:  S 2 = 20.9  W/(cm