Modulation of resistive switching behavior of HfOx film by embedding a thin Al buffer layer

In this work, a thin Al buffer layer was embedded in HfOx film to improve its switching behavior. To investigate the role of the interfacial layer on the switching performance of the film, the micro-structure and chemical composition in and near the interface of the HfOx film was analyzed by XPS and TEM. Larger oxygen-deficiency of the HfOx film near the interface can be obtained due to the chemical reaction. Uniform distribution of switching parameters were observed for the HfOx/Al sample due to the creation of oxygen vacancies around Al ions which favor the formation of a fixed conductive path in the HfOx film, and the diffused Al ions in the film can enhance the local electric field and act as a precursor to induce the growth of filaments. In addition, better dissolution of filaments during the reset process led to an enhanced memory window. Results show that oxygen vacancies and Al ions were both responsible for the improved switching behaviors for the HfOx/Al sample. Finally, the switching mechanism for the HfOx/Al sample was illustrated based on the filamentary model.