Effect of Thermal Annealing on the Structural and Electrical Properties of Hafnium Oxide Films

In this work, thin films of hafnium oxide HfO_x obtained by electron beam deposition were crystallized by thermal annealing in air atmosphere. The relationship between the structural changes occurring as a result of annealing and the electrical properties of the films was determined. It was found that the formation of nanocrystals with a monoclinic structure in the studied films, occurring at annealing temperatures of 500°C and higher, is accompanied by a decrease in their specific conductivity by more than 6 times, which can be associated with a decrease in the number of oxygen vacancies as a result of structure ordering. It was also shown that the specific conductivity of all HfO_x films (pristine and annealed at different temperatures) has a strong dependence on temperature, described by the activation law with an activation energy from 0.86 to 0.93 eV. The obtained data can be used to improve the characteristics of memristive systems and other electronic devices based on hafnium oxide layers.