Post-Annealing Effect on Resistive Switching Performance of a Ta/Mn₂O₃/Pt/Ti Stacked Device

A comparative study of Ta/Mn₂O₃/Pt/Ti stacked capacitor-like resistive switching (RS) devices was performed as a function of the post-annealing process conditions. Compared to as-fabricated RS devices, the post-annealed ones showed higher switching endurance (≈10⁹ RS cycles), good retention characteristics, and narrow operational voltage distribution. To elucidate the microscopic origins of the superior RS performance, various analyses are conducted; and it is revealed that structural and chemical composition changes in post-annealed RS devices can improve the RS performance. In the case of post-annealed samples, unintentionally diffused Ti is observed between the manganese oxide layer and the Pt bottom electrode. Because of the metallic property of diffused Ti, it can be a good electron donor and a center of RS during the formation of a conducting filament (CF) in manganese oxide for nearly uniform RS operation. The highly reliable endurance characteristic is attributed to a TaO_x layer between the Ta top electrode and the manganese oxide. The non-stoichiometric TaO_x layer that is formed during the post-annealing process can play the role of an effective oxygen reservoir, and ≈10⁴ times more RS endurance cycles could be achieved compared to the as-fabricated RS device.