Enhanced resistive switching performance and structural evolution of NiO/Nb2O5−x bilayer memristive device

The development of bilayer models is crucial for enhancing the performance and enabling multifunctionality of next-generation resistive random-access memory (RRAM). However, detailed switching information is still insufficient for multilayer RRAM, necessitating direct observation of the microstructural evolution to clarify its switching mechanism. In this study, the electrical properties of Pt/Nb2O5-x/Pt monolayer devices were improved by introducing a polycrystalline NiO layer, and the resulting Pt/NiO/Nb2O5-x/Pt bilayer devices exhibited a doubling of the endurance and a reduction of the set voltage. The bilayer device also exhibited a long retention time (>104 s) and high on/off ratio of 104. Transmission electron microscopy, X-ray photoelectron spectroscopy, and electron energy-loss spectroscopy revealed that the conductive filament (CF) contained oxygen vacancies. In addition, a funnel-shaped CF was observed in the Pt/NiO/Nb2O5-x/Pt system, with the neck at the NiO/Nb2O5-x interface. This study provides a distinctive viewpoint and an innovative strategy for improving RRAM devices and exploring new applications in electronics.