Tailoring the electrical homogeneity, large memory window, and multilevel switching properties of HfO2-based memory through interface engineering

Abstract

Two-terminal resistive switching (RS) memories have attracted considerable interest for use in storage class memory and in-memory computing applications. However, resistive random-access memory involves limitations such as large RS variability, low endurance, and high operating voltage owing to the stochastic nature of the conductive filament construction and disruption. These issues can be overcome by maximizing the ON/OFF ratio between the low resistive state (LRS, ON-state) and high-resistive state (HRS, OFF-state). In this study, a low-k dielectric (SiO2) layer is inserted between the HfO2 switching layer and high oxygen affinity tantalum oxy-nitride electrode to alleviate the variability and enhance the ON/OFF ratio of Pt/HfO2/SiO2/TaN memory devices. The low-k dielectric barrier layer functions as an oxygen reservoir and can help achieve a high ON/OFF ratio (>104), data retention (104 s), endurance (>1000 cycles), and switching uniformity as well as a low operating voltage at room temperature. The switching time for reversible ON and OFF switching is 0.06 ms and 0.3 ms, respectively. Ohmic behavior in the ON-state and Schottky emission in the high field area of the OFF-state correspond to the current transport conduction processes. Finally, a conducting model based on the variability and ON/OFF ratio enhancement is established to clarify the physical mechanism. The inclusion of a low-k dielectric as an interface layer can enhance the switching properties and ON/OFF ratio, facilitating the use of the proposed device in nonvolatile memory applications.