Effect of thermal annealing on the structural and thermoelectric properties of electrodeposited antimony telluride thin films

• P-type Sb2Te3 thin films were deposited on SUS304 substrate by electrodeposition.
• We performed CV analysis to determine the appropriate potential at −0.1 V.
• Thermal annealing was performed at the temperatures from 200–400 °C for 1 h.
• Impurities (Fe, Cr, Ni) were observed at the annealing temperature over 300 °C.
• The thin film obtained a maximum power factor of 13.6 μW/(cm K2) at 300 °C.

We investigated the effect of thermal annealing on structural and thermoelectric properties of p-type antimony telluride (Sb2Te3) thin films fabricated on a stainless steel (SUS304) substrate by electrodeposition. Antimony telluride thin films were annealed for 1 h at temperatures between 200 and 400 °C. We observed that the as-deposited thin film and thin films annealed at temperatures less than 250 °C possessed a stoichiometric atomic composition (Sb:Te = 40:60) with no impurities from the substrate. At the annealing temperature of 300 °C, we observed a certain amount of impurities (Fe, Cr, Ni) in the thin film. The Seebeck coefficient was decreased but the electrical conductivity was increased for films treated at 300 °C. As a result, the thin film exhibited a maximum power factor of 13.6 μW/(cm·K2). On further increasing the annealing temperature to 400 °C, the film structure and thermoelectric properties were drastically changed. The impurity concentration in the thin film reached approximately 50 at.%. The crystal structure of Sb2Te3 completely disappeared, and instead, other chemical compounds formed by alloying the elements of the thin film and the substrate were observed.