Room Temperature Thermoelectric Properties of Porous BiSbTe Thin Films

Bi$_{(2-x)}$Sb$_{x}$Te$_{3}$ is currently the best known room temperature p-type thermoelectric material, with a ZT value $\sim$ 0.75. We report synthesis of Bi$_{(2-x)}$Sb$_{x}$Te$_{3}$ thin films via pulsed laser deposition using a Bi$_{0.5}$Sb$_{1.5}$Te$_{3}$ target. We have investigated the effect of deposition parameters, including substrate, laser power and inert gas pressure, and annealing conditions on the microstructure, composition and thermoelectric properties of the films. We find a strong dependence of film characteristics on background pressure: The Sb content of the films increases with deposition pressure. Low pressure (1-2 mTorr) depositions yield highly conducting and amorphous films deficient in Te. In addition, we will present a comparison of the thermoelectric properties of porous and dense BiSbTe films, to evaluate film porosity as a means for increasing confinement and improving the thermoelectric power factor.