Thermoelectric properties of Bi2Te3 films electrodeposited with different Te sources

Abstract

The fabrication of semiconducting film by electrodeposition has a high commercial interest because it is a potentially cheap deposition technology, which would enable thin-film to become more prices competitive. In addition, to have highly efficient semiconducting devices a careful control on the electrodeposition process and the presence of dopants or impurities is of critical importance to the final properties of a semiconductor. The impurities incorporated into the deposits can come from high purity reagents. An increase of up to 2.5 times in the power factor is obtained just by using different high purity Te reagents from different suppliers. These results demonstrate that the incorporation of trace impurities from the Bi2Te3 electrochemical bath play an important role in the thermoelectric properties of the film. To make that observation, bismuth telluride (Bi2Te3) films were electrodeposited under the same conditions, but using three different Te powder sources. All the powders tested have a nominal purity equal to or higher than 99.99%. In all the cases, we could achieve films with highly oriented along [110] direction, with the same 2 to 3 Bi/Te ratio, and similar surface, and cross-sectional morphology. However, the thermoelectric properties (electrical conductivity, Seebeck coefficient, and thermal conductivity) depending strongly on the different tellurium powders sources used. Spectrometry of mass with coupling inductive measurements were performed to know which elements influence the final thermoelectric properties of Bi2Te3 films[1, 2].