Improved thermoelectric properties in Zn0.94Al0.06Ox films caused by oxygen defects via oxygen pressure.

Abstract Al-doped ZnO films (Zn 0.94 Al 0.06 O x) can be fabricated by thermal oxidation of evaporated metallic Zn-Al film. Oxygen defects were strongly related to oxygen pressure at a given temperature (500 °C) and duration (3 h). Under oxygen pressure of 0.021 MPa (O 2 -0.021 MPa), the main component was the Zn phase. Zn 0.94 Al 0.06 O x films were formed under oxygen pressure of 0.1 MPa and 0.12 MPa, with the conductivity and Seebeck coefficient improving simultaneously with increased oxygen pressure. The flat particles of the O 2 -0.12 MPa film weakened the electron scattering, leading to increased conductivity. Furthermore, the decrease in oxygen vacancies caused by the higher oxygen pressure increased the Seebeck coefficient. As a result, the power factor of the O 2 -0.12 MPa film was about 30 times greater than that of the O 2 -0.1 MPa film, characterized by an increasing content of singly ionised oxygen. Highlights • Carrier concentration was changed by oxygen pressure in thermal oxidation. • Power factor was affected by content of single ionised oxygen. • Conductivity and Seebeck coefficient increased simultaneously with oxygen pressure. [ABSTRACT FROM AUTHOR]