Optimizations of pulsed plated p and n-type Bi2Te 3-based ternary compounds by annealing in different ambient atmospheres

Abstract

This work presents a comprehensive study of the fabrication and optimization of electrodeposited p- and n-type thermoelectric fi lms. The fi lms are deposited on Au and stainless steel substrates over a wide range of deposition potentials. The infl uence of the preparative parameters such as the composition of the electrolyte bath and the deposition potential are investigated. Furthermore, the p-doped (BixSb1-x) 2Te3and the n-doped BixSb1-x) 2Te3 fi lms are annealed for a period of about 1 h under helium and under tellurium atmosphere at 250 °C for 60h. Annealing in He already leads to signifi cant improvements in the thermoelectric performance. Furthermore, due to the equilibrium conditions during the process, annealing in Te atmosphere leads to a strongly improved fi lm composition, charge carrier density and mobility. The Seebeck coeffi cients increase to values up to ± 182 μ V K-1 for p-doped and-130 μ V K-1 for n-doped materials at room temperature. The power factors also exhibit improvements with 1320 μ W m-1 K-2 and 820 μ W m-1 K-2 for p-doped and n-doped fi lms, respectively. Additionally, in-situ XRD measurements performed during annealing of the fi lms up to 600K under He atmosphere show stepwise improvements of the crystal structure leading to the improvements in thermoelectric parameters. The thermal conductivity is between 1.2 W m-1 K-1 and 1.0 W m -1 K-1 . © 2013 WILEY-VCH Verlag GmbH & Co.