Effect of Ag mixing in thermoelectric Ge2Sb2Te5 thin films

Abstract

Ag-added Ge2Sb2Te5 thin films were prepared by a pulsed-DC co-magnetron sputtering process using Ge2Sb2Te5 and Ag targets. The effect of variation in Ag content through variable power on Ag target was studied on the microstructural and thermoelectric properties of as-deposited and fast annealed thin films at 400 °C in a vacuum. It is found that Ag addition induces enhancement in conductivity. When the power on Ag target is exceeded to a critical power, Ag8GeTe6 phase formation occurs mixed with Ge2Sb2Te5 cubic structure which limits the thermoelectric performance. Best conditions provide the films having a lowest electrical resistivity as 0.98 × 10−4 Ω cm and the maximum power factor as 5.83 × 10−3 W m−1 K−2.