Performance enhancement of HfO2-based resistive random-access memory devices using ZnO nanoparticles.

In this study, resistive random-access memory (ReRAM) devices with ZnO nanoparticles (NPs) are suggested to enhance performance and reduce variation in device switching parameters. The ZnO NPs are formed by annealing ZnO prepared via atomic layer deposition on HfO2, which is verified using transmission electron microscopy (TEM), X-ray diffraction pattern (XRD), and atomic force microscopy (AFM). The depth profile analysis of X-ray photoelectron spectroscopy (XPS) shows that oxygen diffuses from HfO2 to ZnO NPs during annealing. This can be explained by the calculation results using density functional theory where the formation energy of oxygen vacancies is reduced at the interface of ZnO NPs and HfO2 compared to single HfO2. The fabricated ZnO NPs ReRAM demonstrates reduced forming voltage, stable resistive switching behavior, and improved cycle-to-cycle uniformity in a high-resistance state.