Enhanced Thermoelectric Properties of Antimony Telluride Thin Films with Preferred Orientation Prepared by Sputtering a Fan-Shaped Binary Composite Target

Abstract

p-Type antimony telluride (Sb2Te3) thermoelectric thin films were deposited on BK7 glass substrates by ion beam sputter deposition using a fan-shaped binary composite target. The deposition temperature was varied from 100°C to 300°C in increments of 50°C. The influence of the deposition temperature on the microstructure, surface morphology, and thermoelectric properties of the thin films was systematically investigated. x-Ray diffraction results show that various alloy composition phases of the Sb2Te3 materials are grown when the deposition temperature is lower than 200°C. Preferred c-axis orientation of the Sb2Te3 thin film became obvious when the deposition temperature was above 200°C, and thin film with single-phase Sb2Te3 was obtained when the deposition temperature was 250°C. Scanning electron microscopy reveals that the average grain size of the films increases with increasing deposition temperature and that the thin film deposited at 250°C shows rhombohedral shape corresponding to the original Sb2Te3 structure. The room-temperature Seebeck coefficient and electrical conductivity range from 101 μV K−1 to 161 μV K−1 and 0.81 × 103 S cm−1 to 3.91 × 103 S cm−1, respectively, as the deposition temperature is increased from 100°C to 300°C. An optimal power factor of 6.12 × 10−3 W m−1 K−2 is obtained for deposition temperature of 250°C. The thermoelectric properties of Sb2Te3 thin films have been found to be strongly enhanced when prepared using the fan-shaped binary composite target method with an appropriate substrate temperature.