Effect of substrate rotation and rapid thermal annealing on thermoelectric properties of Ag-doped Sb2Te3 thin films

In this work, homogeneous Ag-doped Sb2Te3 (AST) thin films were prepared using the rf magnetron sputtering technique. Thermoelectric properties of AST films have been investigated in terms of various substrate rotation speeds (20, 40, 60, and 80 rpm) and rapid post-thermal treatments at 250 oCin a vacuum. It was found that the thickness of AST films decreases with the increase in substrate rotation speeds. An Ag atomic composition slightly increases and the other Sb and Te atomic compositions slightly decrease with the increase of substrate speed rotations. The post-thermal treatment improved film crystallinity. Carrier scatterings at the grain boundaries tend to increase the resistivity and the Seebeck coefficient. The maximum power factor of 4.60 mW m- 1K-2 (rho = 19 mu omega m, S = 298 mu VK-1) is obtained in the AST thin films prepared with the substrate rotation speed of 60 rpm. The practical application of AST films was also reported via a thermoelectric module of five p-AST/n-Bi2Te3thin-film pairs with its achieved output power of 1.6 nW at Delta T = 20 K.