Facile synthesis and nanoscale related physical properties of core-shell structured CuO/ZnO nanorods on Si substrate

Core-shell structured CuO/ZnO nanorods (NRs) consisting of monocrystalline p-type CuO core covered with the nanocrystalline n-type ZnO shell were directly fabricated on Si substrate through depositing ZnO on the asgrown CuO NRs. The in-situ current-voltage (I-V) characterization of CuO/ZnO NRs by conducive atomic force microscopy (C-AFM) revealed a novel p-type based self-rectifying resistive switching behavior, providing an effective solution to suppress sneak current issue for nonvolatile memory applications. The special switching characteristic and better rectification can be explained by the asymmetric back-to-back structure of C-AFM tip/ZnO and ZnO/CuO under different electric field directions due to the special core-shell structured p-n junction. Compared with bare CuO core, the red-shift and increased photoluminescence (PL) intensity for the CuO/ZnO NRs have been attributed to the deposited shell and special heterostructure. These results demonstrated that the electrical and optical properties of CuO NRs can be successfully tuned by introducing a ZnO shell, which is important for potential applications in functional nanodevices at room temperature.