Annealed AlOx film with enhanced performance for bipolar resistive switching memory

Highlights: • Forming-free, low set/reset voltage and good stability are achieved. • Different annealing temperatures were compared and analyzed. • The role of oxygen vacancies in the resistive switching behaviors is analyzed. • The annealing treatment under N₂ increased the oxygen vacancies. Although some efforts have been dedicated to explore aluminum oxide (AlO_x) based memory devices in the past few years, the disappointed stability and complicated fabrication process strictly limit its wide applications. In this study, we introduce the annealing treatment as an effective method to substantially improve the non-volatile resistive switching performance of AlO_x film based resistive memory devices. Fabricated by radio frequency magnetron sputtering method at room temperature, the AlO_x resistive memory devices are subsequently annealed in nitrogen atmosphere with the temperature range from 100 °C to 500 °C. The devices exhibit enhanced bipolar resistive switching properties with forming-free nature, high HRS/LRS ratio (>10³), long retention time (>10⁴s) and statistical switching performance (>200 cycles). The conductive filaments constructed by oxygen vacancies has been demonstrated as a dominant factor for the resistive switching behavior in the AlO_x film based memory devices, and introducing oxygen-free atmosphere annealing treatment will increase the proportion of oxygen vacancies, thus resulting in a considerable resistive switching improvement. Our work proves the great potential of annealed AlO_x film as resistive switching layer in resistive random access memory devices, and also paves the way for optimization of relevant devices based on binary metal oxides.