Enhanced resistive switching characteristics in p/CuO-n/ZnO bilayer structure memory cells

In this paper, the resistive switching characteristics and underlying mechanisms of bilayer p/CuO-n/ZnO device are comprehensively investigated. Owing to the presence of p-n junction, the current-voltage (I-V) curve of the bilayer CuO-ZnO device exhibits asymmetric characteristics. To elucidate the internal resistive switching mechanisms, a dual model incorporating p-n junction interfacial effects and oxygen-vacancy-filamentary conduction is proposed. Compared with the single layer ZnO device, the bilayer CuO-ZnO device exhibits enhanced retention and endurance performances. This improvement is attributed to the built-in electric field at the p-n junction, which stabilizes charge carrier dynamics, and the ordered migration of oxygen vacancies at the interface, which suppresses the random formation of conductive filaments. Furthermore, the I-V curve of bilayer CuO-ZnO device exhibits a remarkable photoelectric response under ultraviolet (UV, 365 nm) illumination. This finding offers a valuable reference for optically controlled resistive switching behavior of ZnO based memory cells, thereby potentially contributing to the development of the related optoelectronic applications.