阻变效应的光场调控规律及机理研究

Resistive random access memory (RRAM) is a very promising high-speed, high-density and low-power nonvolatile memory candidate. The data are usually recorded via reversible formation and rupture of nano conducting filaments in storage media. However, nano conducting filaments are intrinsically metastable at room temperature, making RRAM almost impossible to own low-power operation and long-time data retention simultaneously. To solve this issue, we propose the modulation of resistive switching effect by light and plan to research it based on RRAM devices using BiFeO3 films with good resistive switching and photoelectric characteristics as storage media. The research will start with the fabrication of BiFeO3-based RRAM devices with various configurations, sizes and microstructures. Then, by systematically characterizing their resistance evolutions under different electric field and light loading methods, ion transport processes and redox reactions in these devices will be revealed, and the effects of light on resistive switching as well as data retention characteristics of these devices and related mechanisms will be clarified. Finally, a light loading method that enables RRAM to own low-power operation and long-time data retention simultaneously is expected to be developed. These results would provide a theoretical basis and guide for performance enhancement of RRAM.

阻变存储器是一种有前途的高速、高密度和低功耗的新型非易失性存储技术。通常，阻变存储器基于存储介质中纳米导电细丝的可逆通断实现数据存储，但纳米导电细丝为本征的室温亚稳态相，使得阻变存储器难以兼具低擦写功耗和高稳定数据保持特性，严重制约了其综合性能。针对这一问题，本项目提出“利用光场来调控阻变效应”，拟选用兼具优异阻变与光电特性的铁酸铋薄膜作为存储介质构建阻变器件，通过系统表征不同电场、光场加载方式下各种构型、尺寸以及微结构器件的电阻状态演化过程，澄清电场、光场协同作用下固体介质中的离子输运与氧化还原反应过程，阐明光场对器件阻变过程与数据保持特性的调控规律和机理，进而发展出使得器件兼具低擦写功耗和高稳定数据保持特性的光场加载方式，为阻变存储器的综合性能优化提供理论依据和指导。

针对大数据、人工智能等新兴信息技术发展对新型高密度和多功能信息存储器的迫切需求，本项目以阻变存储器为研究对象，通过选用光敏半导体介质构建器件，研究了光、电协同调控器件阻变特性的规律和机理，并探索了器件在高密度存储和神经功能仿生方面的潜在应用，代表性进展包括：（1）设计制备了“ITO/Nb:SrTiO3”异质结光电阻变器件，具有可电调控的部分易失性光响应特性，由此实现了人眼视觉功能仿生；（2）设计制备了“ITO/CeO2–x/Pt”三明治结构的光电阻变器件，具有可电调控的光激励阈值响应特性，由此实现人眼光痛觉功能仿生；（3）设计制备了具有稳定电导量子化效应的“Pt/HfOx/ITO”阻变器件，观测到了以0.5倍单原子接触电导为间隔的连续32个量子电导态，可望用于5bit/cell的超高密度数据存储。相关结果可为我国发展具有自主知识产权的高密度和多功能信息存储材料与器件提供重要的理论支撑。