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

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 100A degrees C to 300A degrees C in increments of 50A degrees 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 200A degrees C. Preferred c-axis orientation of the Sb2Te3 thin film became obvious when the deposition temperature was above 200A degrees C, and thin film with single-phase Sb2Te3 was obtained when the deposition temperature was 250A degrees 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 250A degrees C shows rhombohedral shape corresponding to the original Sb2Te3 structure. The room-temperature Seebeck coefficient and electrical conductivity range from 101 mu V K-1 to 161 mu V K-1 and 0.81 x 10(3) S cm(-1) to 3.91 x 10(3) S cm(-1), respectively, as the deposition temperature is increased from 100A degrees C to 300A degrees C. An optimal power factor of 6.12 x 10(-3) W m(-1) K-2 is obtained for deposition temperature of 250A degrees 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.