Low-Temperature ALD of SbO_x /Sb₂ Te₃ Multilayers with Boosted Thermoelectric Performance

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 (Sb₂ Te₃ ) thin film with sub-nanometer layers of antimony oxide (SbO_x ) 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 Sb₂ Te₃ and SbO_x . A remarkable power factor of 520.8 µW m^-1 K^-2 is attained at room temperature when the cycle ratio of SbO_x and Sb₂ Te₃ 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 SbO_x /Sb₂ Te₃ interface, the presence of the SbO_x sub-layer induces the confinement effect and strain forces in the Sb₂ Te₃ 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.