Thickness and Grain Size Effects on Thermal Transport of Post-Annealed Antimony Telluride Thin Films

We report on the effect of the thickness and grain size on the thermal transport properties of antimony telluride (Sb2Te3) thin films in the temperature range of 20-300 K using a four-point-probe 3-omega method. For this study, 100-, 400-, and 500-nm-thick Sb2Te3 films were prepared by radio frequency magnetron sputtering. The average thermal conductivity of the films was determined to be between 0.8 and 3.9 W/m . K in the temperature range of 20-300 K, revealing a strong thickness and temperature dependence of the thermal transport properties of the films. We suggest that this reduction in the thermal conductivity of the films, compared to the bulk, may be attributed to the enhanced phonon scattering from the grain boundary that occurs when decreasing the thickness to 100 nm. To further investigate the effects of the thickness and grain size, the experimental results of the films were theoretically analyzed using the Sondheimer model, which showed a good agreement with the measured values, indicating that the thermal conductivity decreases appreciably from the bulk values.