Observation of Resistive Switching Behavior in Crossbar Core–Shell Ni/NiO Nanowires Memristor

Abstract

The crossbar structure of resistive random access memory (RRAM) is the most promising technology for the development of ultrahigh-density devices for future nonvolatile memory. However, only a few studies have focused on the switching phenomenon of crossbar RRAM in detail. The main purpose of this study is to understand the formation and disruption of the conductive filament occurring at the crossbar center by real-time transmission electron microscope observation. Core-shell Ni/NiO nanowires are utilized to form a cross-structure, which restrict the position of the conductive filament to the crosscenter. A significant morphological change can be observed near the crossbar center, which results from the out-diffusion and backfill of oxygen ions. Energy dispersive spectroscopy and electron energy loss spectroscopy demonstrate that the movement of the oxygen ions leads to the evolution of the conductive filament, followed by redox reactions. Moreover, the distinct reliability of the crossbar device is measured via ex situ experiments. In this work, the switching mechanism of the crossbar core-shell nanowire structure is beneficial to overcome the problem of nanoscale minimization. The experimental method shows high potential to fabricate high-density RRAM devices, which can be applied to 3D stacked package technology and neuromorphic computing systems.

Recent Advances in Memristive Materials for Artificial Synapses

“…Through this device, the PPF behavior is obtained with a pulse amplitude of 2 V. The SRDP behaviors with different pulse frequencies ranging from 0.33 to 10 Hz are also observed. Ting et al in 2017 reported on the resistive switching properties of Ni@NiO core–shell NWs with a cross structure. The cross structure achieves the possibility of confining the switching region.…”

“…There are various possible materials that can achieve memristive properties. These include binary oxides, oxide perovskites, polymers, bioinspired materials, 2D materials, halide perovskites, and low‐dimensional materials as shown in Figure . Each material has advantages in the working mechanism and/or properties of itself, which results in improved performances of memristive devices and artificial synapses.…”

Overview of Resistive Random Access Memory (RRAM): Materials, Filament Mechanisms, Performance Optimization, and Prospects

“…On the other hand, inorganic materials can be manufactured by simple processes, show stable performance, have low cost, and are receiving extensive attention from researchers. We mainly introduce solid electrolyte, oxides, and low‐dimension system of the inorganic resistive switching materials . Binary oxides have attracted attention in the electronics field due to their simple structure, ease of control in material composition, low cost, and compatibility with conventional processes.…”

“…Thereafter, TiO 2 materials were introduced that could reduce the memory switching voltage and achieve good endurance characteristics over 10 4 cycles. NiO materials can improve the ON/OFF ratio, while SiO 2 materials serve as a functional layer and greatly improve the data retention characteristics. Moreover, there are also a large number of binary oxides such as HfO 2 MnO 2 , and so on .…”

“…The ECM is mostly used to explain the principle of devices with metal active electrodes with relatively high mobility, such as Ag, Cu, Ni, etc . The formation of single Ag filaments of the Ag/Ag‐As 2 S 3 /Au device was observed by an optical micrograph and reported in 1976 by Hirose .…”