Low-Temperature ALD of SbOx/Sb2Te3 Multilayers with Boosted Thermoelectric Performance

Abstract

Nanoscale superlattice (SL) structures have proven to be effective in enhancing the thermoelectric (TE) properties of thin films. Herein, the main phase of antimony telluride (Sb2Te3) thin film with sub-nanometer layers of antimony oxide (SbOx) is synthesized via atomic layer deposition (ALD) at a low temperature of 80 °C. The SL structure is tailored by varying the cycle numbers of Sb2Te3 and SbOx. A remarkable power factor of 520.8 µW m−1 K−2 is attained at room temperature when the cycle ratio of SbOx and Sb2Te3 is set at 1:1000 (i.e., SO:ST = 1:1000), corresponding to the highest electrical conductivity of 339.8 S cm−1. The results indicate that at the largest thickness, corresponding to ten ALD cycles, the SbOx layers act as a potential barrier that filters out the low-energy charge carriers from contributing to the overall electrical conductivity. In addition to enhancing the scattering of the mid-to-long-wavelength at the SbOx/Sb2Te3 interface, the presence of the SbOx sub-layer induces the confinement effect and strain forces in the Sb2Te3 thin film, thereby effectively enhancing the Seebeck coefficient and reducing the thermal conductivity. These findings provide a new perspective on the design of SL-structured TE materials and devices.