Resistive switching properties and mechanisms of La doped ZnO thin film memory cells

In this paper, the memory cells based on ZnO thin films with various La concentrations (x% La:ZnO, x = 0, 2, 4, 6) are fabricated using the sol-gel spin coating method. Systematic investigations reveal that La doping significantly enhances the memory window, operational stability, and forming voltage reduction of the fabricated devices. Particularly, the 6%La:ZnO device achieves optimal resistive switching behaviors, including an enhanced on/off ratio of two orders of magnitude, a long retention time of up to 104 s, and a stable endurance of up to 100 cycles. X-ray photoelectron spectra analysis demonstrates that La incorporation effectively improves oxygen vacancy concentration in ZnO thin film. The improvement of resistive switching characteristics should be attributed to the increased oxygen vacancy concentration, which could provide more stable conductive filaments. These results demonstrate that La doping serves as a practical and effective strategy for optimizing the resistive switching properties of ZnO memory devices.