Impact of Rapid Thermal Annealing and Oxygen Concentration on Symmetry Bipolar Switching Characteristics of Tin Oxide-Based Memory Devices.

In this study, tin oxide (SnO) resistive random-access memory (RRAM) thin films were fabricated using the thermal evaporation and radiofrequency and dc frequency sputtering techniques for metal-insulator-metal (MIM) structures. The fabrication process began with the deposition of a silicon dioxide (SiO) layer onto a silicon (Si) substrate, followed by the deposition of a titanium nitride (TiN) layer to serve as the bottom electrode. Subsequently, the tin oxide (SnO) layer was deposited as the resistive switching insulator. Two types of top electrodes were developed to investigate the influence of different oxygen concentrations on the bipolar switching, electrical characteristics, and performance of memory devices. An aluminum (Al) top electrode was deposited using thermal evaporation, while a platinum (Pt) top electrode was deposited via dc sputtering. As a result, two distinct metal-insulator-metal (MIM) memory RRAM device structures were formed, i.e., Al/SnO/TiN/SiO/Si and Pt/SnO/TiN/SiO/Si. In addition, the symmetry bipolar switching characteristics, electrical conduction mechanism, and oxygen concentration factor of the tin oxide-based memory devices using rapid thermal annealing and different top electrodes were determined and investigated by ohmic, space-charge-limit-current, Schottky, and Poole-Frenkel conduction equations in this study.