Impact of the Atomic Layer-Deposited Ru Electrode Surface Morphology on Resistive Switching Properties of TaO_x-Based Memory Structures

Abstract

Resistive switching (RS) device behavior is highly dependent on both insulator and electrode material properties. In particular, the bottom electrode (BE) surface morphology can strongly affect RS characteristics. In this work, Ru films with different thicknesses grown on a TiN layer by radical-enhanced atomic layer deposition (REALD) are used as an inert BE in TaO x -based RS structures. The REALD Ru surface roughness is found to increase by more than 1 order of magnitude with the increase in the reaction cycle number. Simultaneously, a wide range of RS parameters, such as switching voltage, resistance both in low and high resistance states, endurance, and so forth, monotonically change. A simplified model is proposed to explain the linkage between RS properties and roughness of the Ru surface. The field distribution was simulated based on the observed surface morphologies, and the resulting conducting filament formation was anticipated based on the local field enhancement. Conductive atomic force microscopy confirmed the theoretical expectations.

Tin Oxide Nanorod Array-Based Photonic Memristors with Multilevel Resistance States Driven by Optoelectronic Stimuli

“…Nonetheless, the ON/OFF ratio, uniformity of resistances of LRS and HRS of the Al/SnO x (40 nm)/FTO device under the dark is better than the Al/SnO x (20 nm)/FTO and Al/SnO x (60 nm)/FTO devices. Further, there are several reports which suggest that the active layer thickness, the bottom electrode roughness, and the operating voltages are mutually related. − The lower active layer thickness and the higher bottom electrode roughness often lead to lower electroforming voltage in RS devices. But, the device failure rate significantly increases.…”

Deterministic Conductive Filament Formation and Evolution for Improved Switching Uniformity in Embedded Metal-Oxide-Based Memristors─A Phase-Field Study

“…However, due to the difficulty in fabricating a high-quality thin film layer, the synthesized metal oxide devices always suffer from stochasticity in operation voltages, current ON/OFF ratios, switching speeds, etc., among different devices, or in the same device among different switching cycles, , which is one of the critical challenges limiting the widespread application in next-generation memory and neuromorphic computing applications. This stochasticity mainly stems from two major reasons: (a) the complex nature of the electrode/oxide interface, − and (b) the variable chemical properties of the complicated microstructure of the metal oxide layer. , These stochastic properties influence both the electroforming process and the subsequent resistive switching behavior. Extensive experimental studies have been made to understand the stochasticity in RRAMs.…”

Effect of Electrode Nanopatterning on the Functional Properties of Ta/TaOx/Pt Resistive Memory Devices

“…Alternatively, the variation in the Mo bottom electrode (BE) roughness in Mo/SiO x /Ti/Au structures induced the growth of a “grainy” amorphous SiO x layer on top, where the boundaries between the “grains” were claimed to act as precursors for the formation of oxygen vacancies and thus affected the RS properties . Recently, the effect of varying the BE morphology on the properties of TaO x -based RS devices has been reported. , In both works, the authors demonstrated the significant impact of the electrode microstructure on the functional parameters of RS devices as well as the location of CFs, but such an approach is difficult to use for practical applications once well-defined and reproducible parameters are needed. In this work, a single nanosize heterogeneity was introduced in a highly controllable way on the flat Pt BE in the well-studied Ta/TaO x /Pt-based RS devices, and the effect of such nanopatterning on the functional properties of RS devices was investigated.…”