Low thermal conductivity and related thermoelectric properties of Zn4Sb3 and CoSb3 thin films

Thermal conductivity and other thermoelectric properties were investigated on beta-Zn4Sb3 and CoSb3 thin films. They are prepared by co-deposition of the specific sets of Zn, Sb and Co targets by RF magnetron sputtering. Thermal conductivity measurement was performed based on an AC calorimetry method using LaserPIT. The Zn4Sb3 thin films investigated are Zn-rich with respect to the stoichiometric composition. Their thermal conductivity decrement is proportional to the reciprocal film thickness. A nano-scale grain size in a similar to350 nm-thick film specimen gives arise to an almost 50% reduction in its thermal conductivity (similar to0.5 W/mK) at room temperature. Low electrical resistivity and high Seebeck coefficient can be achieved simultaneously in the film specimen with property controlled thickness and microstructure. A ZT of 1.2 at similar to460 K has been obtained for the similar to350 nm thick Zn4Sb3 film specimen. The minimum thermal conductivity of about 1.1 W/mK was obtained in a similar to325 nm-thick CoSb3 film specimen at room temperature.