Demonstration of synaptic and resistive switching characteristics in W/TiO2/HfO2/TaN memristor crossbar array for bioinspired neuromorphic computing

• 作者: Muhammad Ismail Umesh Chand Chandreswar Mahata Jamel Nebhen Sungjun Kim
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2022,（1）
• 页码范围: 94-102
• 页数: 9页
• 语种: 英文

摘要

In this study,resistive random-access memory (RRAM)-based crossbar arrays with a memristor W/TiO2/HfO2/TaN structure were fabricated through atomic layer deposition (ALD) to investigate synap-tic plasticity and resistive switching (RS) characteristics for bioinspired neummorphic computing.X-ray photoelectron spectroscopy (XPS) was employed to explore oxygen vacancy concentrations in bilayer TiO2/HfO2 films.Gaussian fitting for O1s peaks confirmed that the HfO2 layer contained a larger num-ber of oxygen vacancies than the TiO2 layer.In addition,HfO2 had lower Gibbs free energy (AG°=-1010.8 kJ/mol) than the TiO2 layer (ΔG°=-924.0 kJ/mol),resulting in more oxygen vacancies in the HfO2 layer.XPS results and AG° magnitudes confirmed that formation/disruption of oxygen-based conductive filaments took place in the TiO2 layer.The W/TiO2/HfO2/TaN memristive device exhibited excellent and repeatable RS characteristics,including superb 103 dc switching cycles,outstanding 107 pulse endurance,and high-thermal stability (104 s at 125 ℃) important for digital computing systems.Furthermore,some essential biological synaptic characteristics such as potentiation-depression plasticity,paired-pulse facil-itation (PPF),and spike-timing-dependent plasticity (STDP,asymmetric Hebbian and asymmetric anti-Hebbian) were successfully mimicked herein using the crossbar-array memristive device.Based on exper-imental results,a migration and diffusion of oxygen vacancy based physical model is proposed to describe the synaptic plasticity and RS mechanism.This study demonstrates that the proposed W/TiO2/HfO2/TaN memristor crossbar-array has a significant potential for applications in non-volatile memory (NVM) and bioinspired neuromorphic systems.