Sb content dependent thermoelectric properties of the p-type ZnO:Sb films fabricated by oxidation method

Highlights: • Stable p-type ZnO:Sb film were obtained with 5.32% Sb by oxidation method. • High carrier concentration (10²⁰ cm⁻³) relates to O sites substituted by Sb³⁺ ions. • Resistivity has a sharply reduction with Sb content from 0.228 Ω·m to 4.68 × 10⁻⁵ Ω·m. • High Sb content (5.32%) is easy to form Zn₄Sb₃ and ZnSb compound in wurtzite ZnO. It is important to fabricate stable p-type ZnO:Sb thermoelectric (TE) films for the p-n homojunction TE devices that convert waste heat directly into electricity. In this study, the ZnO:Sb films with different Sb contents were prepared by oxidizing evaporated Zn-Sb films in oxygen. The film with a high Sb content (5.32%) is easy to form Zn₄Sb₃ and ZnSb compound in the wurtzite ZnO. The resistivity has a sharply reduction with the Sb content from 0.228 Ω·m of 3.95% Sb to 4.68 × 10⁻⁵ Ω·m of 5.32% Sb. The lowest resistivity is lower at least one order of magnitude than the results of others with the similar Sb content. The Seebeck coefficient indicates that the 5.32% Sb film remains stable p-type conduction. The carrier concentration is about 10²⁰ cm⁻³ and is higher at least one order of magnitude than the other results. Raman analysis indicates that the peak of $E_2^{\text{high}}$ related O sublattice vibrations indicates that the O sites are substituted by Sb³⁺ ions, which increases the carrier concentration. However, the mobility is relatively weak because the intrinsic host lattice defects activated as vibrating complexes. The power factor of the p-type ZnO:Sb of the 5.32% Sb film at 427 °C is 46.79 μW/m·K².