Improving the thermoelectric properties of thick Sb2Te3 film via Cu doping and annealing deposited by DC magnetron sputtering using a mosaic target

Abstract

Thick Cu-doped Sb2Te3 films were deposited on flexible substrate by DC magnetron sputtering from a mosaic Cu–Sb2Te3 target. The Cu-doped Sb2Te3 films were vacuum annealed to improve their thermoelectric properties. Density functional theory was used to clarify the internal mechanism of the Cu doped into the Sb2Te3 system. The results showed that Cu substitution on a Sb site induced electronic states or impurity peaks of Sb2Te3 at a valence band maximum. The carrier concentration of the Cu-doped Sb2Te3 films increased as the Cu-doped concentration increased. However, the crystallite size and Seebeck coefficient of the Cu-doped Sb2Te3 films decreased as the Cu-doped concentration increased. Post-annealing treatment improved the microstructure and thermoelectric properties of the Cu-doped Sb2Te3 films. The maximum electrical conductivity and power factor values of 754.20 S/cm at 50 °C and 1.56 10−3 W/mK2 at 100 °C were obtained in the annealed film with a Cu-doped concentration of 3 at%.