Conductivity of Hafnium Oxide Films Obtained by Electron-Beam Sputtering

Hafnium oxide films HfOx with a thickness of about 40 nm were obtained by electron beam sputtering at different oxygen flow rates in the chamber. The electrophysical properties of the films were studied in air and in a vacuum. It has been shown that the temperature dependences of film conductivity, measured in a vacuum in the temperature range from 20 to 180 degrees C, have an activation character with an activation energy of 0.82 +/- 0.02 eV. It is assumed that in the resulting films, charge transfer is determined by the activation of electrons into the conduction band from the donor level associated with oxygen vacancies. It was found that the conductivity of the films in air changes greatly with varying the oxygen flow, while in a vacuum, the conductivity is practically independent of the oxygen flow. This indicates significant differences in the surface properties of the films obtained at different oxygen flows in the chamber during the deposition process.