Resistive switching (RS) devices are emerging electronic components that could have applications in multiple types of integrated circuits, including electronic memories, true random number generators, radiofrequency switches, neuromorphic vision sensors, and artificial neural networks. The main factor hindering the massive employment of RS devices in commercial circuits is related to variability and reliability issues, which are usually evaluated through switching endurance tests. However, we note that most studies that claimed high endurances >106 cycles were based on resistance versus cycle plots that contain very few data points (in many cases even <20), and which are collected in only one device. We recommend not to use such a characterization method because it is highly inaccurate and unreliable (i.e., it cannot reliably demonstrate that the device effectively switches in every cycle and it ignores cycle-to-cycle and device-to-device variability). This has created a blurry vision of the real performance of RS devices and in many cases has exaggerated their potential. This article proposes and describes a method for the correct characterization of switching endurance in RS devices; this method aims to construct endurance plots showing one data point per cycle and resistive state and combine data from multiple devices. Adopting this recommended method should result in more reliable literature in the field of RS technologies, which should accelerate their integration in commercial products.
11 August 2021 in ACS Applied Electronic Materials
This study investigates the resistive switching characteristics and underlying mechanism in 2D layered hexagonal boron nitride (h-BN) dielectric films using conductive atomic force microscopy. A combination of bipolar and threshold resistive switching is observed consistently on multi-layer h-BN/Cu stacks in the low power regime with current compliance (Icomp) of less than 100 nA. Standard random telegraph noise signatures were observed in the low resistance state (LRS), similar to the trends in oxygen vacancy-based RRAM devices. While h-BN appears to be a good candidate in terms of switching performance and endurance, it performs poorly in terms of retention lifetime due to the self-recovery of LRS state (similar to recovery of soft breakdown in oxide-based dielectrics) that is consistently observed at all locations without requiring any change in the voltage polarity forIcomp~1–100 nA.
Higher memory density and faster computational performance of resistive switching cells require reliable array‐accessible architecture. However, selecting a designated cell within a crossbar array without interference from sneak path currents through neighboring cells is a general problem. Here, a highly doped n++ Si as the bottom electrode with Ni‐electrode/HfOx/SiO2 asymmetric self‐rectifying resistive switching device is fabricated. The interfacial defects in the HfOx/SiO2 junction and n++ Si substrate result in the reproducible rectifying behavior. In situ transmission electron microscopy is used to quantitatively study the properties of the morphology, chemistry, and dynamic nucleation–dissolution evolution of the chains of defects at the atomic scale. The spatial and temporal correlation between the concentration of oxygen vacancies and Ni‐rich conductive filament modifies the resistive switching effect. This study has important implications at the array‐level performance of high density resistive switching memories.