Influence of Sputtering Power Density on the Thermoelectric and Mechanical Properties of Flexible Thermoelectric Antimony Telluride Films Deposited by DC Magnetron Sputtering

Antimony telluride (Sb2Te3) films were deposited on flexible polyimide substrates by DC magnetron sputtering technique using a 99.9% alloy Sb2Te3 target. We measured structural, electrical, thermoelectric and mechanical properties with sputtering power density in the range 30-50 W. X-ray diffraction confirmed that all Sb2Te3 films have high crystallinity with a significant preferential growth along the (015) plane. Surface morphologies were verified by scanning electron microscope: deposited film grain size increased with sputtering power density. The elemental composition was determined by energy dispersive x-ray spectroscopy. Electrical transport properties, carrier concentration, was measured by Hall effect measurement at room temperature. Electrical conductivity and Seebeck coefficient were simultaneously measured by a DC four-terminal method (ZEM-3). The power factor was strongly dominated by electrical conductivity, leading to a maximum of 1.95 mW/K(2)m with sputtering power 45 W at 300 degrees C. The wettability test, based on the contact angle, evaluated surface energy and hydrophilicity. Nanoindentation was measured on a NHT2 CSM Instrument with diamond Berkovich indenter (B-P 31) at room temperature. The hardness and elastic modulus of deposited Sb2Te3 films increased with the power density.