Influence of Substrate Temperature on Structural and Thermoelectric Properties of Antimony Telluride Thin Films Fabricated by RF and DC Cosputtering

Antimony and tellurium were deposited on BK7 glass using direct-current magnetron and radiofrequency magnetron cosputtering. Antimony telluride thermoelectric thin films were synthesized with a heated substrate. The effects of substrate temperature on the structure, surface morphology, and thermoelectric properties of the thin films were investigated. X-ray diffraction patterns revealed that the thin films were well crystallized. c-Axis preferred orientation was observed in thin films deposited above 250A degrees C. Scanning electron microscopy images showed hexagonal crystallites and crystal grains of around 500 nm in thin film fabricated at 250A degrees C. Energy-dispersive spectroscopy indicated that a temperature of 250A degrees C resulted in stoichiometric Sb2Te3. Sb2Te3 thin film deposited at room temperature exhibited the maximum Seebeck coefficient of 190 mu V/K and the lowest power factor (PF), S (2) sigma, of 8.75 x 10(-5) W/mK(2). When the substrate temperature was 250A degrees C, the PF increased to its highest value of 3.26 x 10(-3) W/mK(2). The electrical conductivity and Seebeck coefficient of the thin film were 2.66 x 10(5) S/m and 113 mu V/K, respectively.