Endurance improvement and resistance stabilization of transparent multilayer resistance switching devices with oxygen deficient WOx layer and heat dissipating AlN buffer layer

In this study, indium tin oxide (ITO), zinc oxide (ZnO), tungsten oxide (WO_x), and aluminum nitride (AlN) were employed to fabricate and investigate four transparent resistive random access memory (ReRAMs) structures: ITO/ZnO/ITO (structure 1), ITO/WO₃/ZnO/ITO (structure 2), ITO/WO_x(x 3/ZnO/ITO (structure 3), and ITO/WO_x(x 3/ZnO/AlN/ITO (structure 4). Structure 4 exhibited less variation in low-resistance states, lower operating voltages, and higher endurance compared with other structures. This phenomenon was attributed to the oxygen-deficient WO_x layer in structure 4, which acted as an oxygen ion reservoir for efficient resistive changes, and the WO₃ layer limited the filament rupture and formation region. Moreover, the high thermal conductivity of the AlN layer alleviated the thermally activated ion movement of the ReRAM and strengthened the high-resistance state. Structure 4 was found to be the optimal structure, with median operating voltages 1.6 V for SET operations and − 1.0 V for RESET operations, retention of > 10⁴ s at 200 °C, and endurance of 10⁴ cycles with a resistance ratio of over 20. Structure 4 exhibited extremely high stability in both low- and high-resistance states during cycling. The transmittance of structure 4 was 85.49%, which is suitable for optoelectronic applications.