氧化还原类阻变存储器中金属性导电细丝形成机理研究

Resistive random access memory (RRAM) combines the functions of information storage and treatment. The characterizations of nonvolatile, high speed, low-energy operations and high density make RRAM as a hot topic of research and development in the field of next generation storage memory. The research of formation/rupture mechanisms of conductive filaments with a metallic behavior at the low resistive state of redox processes based RRAM, and the understanding of the active switching region during electrical operation, have been a longstanding desire since the 1960s. Embarking on the related studies is significant not only for the research and development of RRAM, but also for advancing its practical applications. In this proposal, metals, such as silver, copper, aluminum，titanium and platinum, are selected for the electrodes, as well as 30-50nm thick oxides, nitrides and organic compounds are used for the storage medium. Through the complementary characterizations of the interface of metal/storage medium, and the active switching region, the formation/rupture mechanisms of conductive filaments with the metallic behavior arising from different conditions, such as electrodes, nanometallic particles and redox processes of cations of the storage medium will be clarified. Meanwhile, the dynamic model will be constructed on the basis of the micro-process of the connection and disconnection of the filaments, subsequently, a theory will be proposed, which will serve as a guide for the further research and development of RRAM. This process also provides a scientific basis for the usage of Redox RRAM for the simulation of the artificial cognition memory and synapse in neuromorphic systems.

阻变存储器兼具信息存储和处理的功能，非易失性、高速度、低功耗和高密度等特点使其成为下一代存储器研发的热点之一。研究氧化还原类型阻变存储器（Redox RRAM)的低阻态金属性导电细丝的形成与断开机制，诠释阻变激活区电操作过程，是自上世纪六十年代以来科学家们一直渴望解决的关键科学问题，开展相关研究对于阻变存储器的研发和推进其实用化进程具有重要的意义。本项目拟选用金属银、铜、铝、钛、铂作为电极、30-50纳米厚氧化物、氮化物和有机化合物等作为存储介质构建存储器；通过对"金属/介质层"界面和阻变激活区的精细表征，阐明不同来源（包括电极、纳米金属颗粒、介质层阳离子氧化还原）的金属性导电细丝形成与断开机制。基于连通与截断的微观过程，建立相应的动力学模型，进而发展出指导阻变存储器研发的相关理论，同时也为Redox RRAM用于模拟人工认知记忆和神经网络中的突触提供科学依据。

阻变存储器兼具信息存储和处理的功能，非易失性、高速度、低功耗和高密度等特点使其成为下一代存储器研发的热点之一。研究氧化还原类型阻变存储器（Redox RRAM)的低阻态金属性导电细丝的形成与断开机制，诠释阻变激活区电操作过程，是自上世纪六十年代以来科学家们一直渴望解决的关键科学问题，开展相关研究对于阻变存储器的研发和推进其实用化进程具有重要的意义。项目选用金属银、铜、铝、钛、铂作为电极、氧化物、氮化物和有机化合物（P3HT:PCBM、PEDOT:PSS）等作为存储介质构建存储器，通过平面器件结构解析了电极材料进入介质层形成金属导电细丝生长动力学过程，调控阻变激活区电操作过程在多个材料体系中观察到金属性和氧空位导电细丝的量子导电行为；探索了介质层中掺入的金属纳米颗粒或介质层阳离子在电场作用或热处理下演化为金属性导电细丝的过程，通过对AlN/Cu/AlN薄膜进行快速退火处理在AlN薄膜中引入Cu纳米团簇成功制备出Pt/AlN:Cu/Pt单极性阻变存储器，利用插入超薄的Ta金属纳米层成功调控了Ta2O5的阻变行为，制备出操作电流小、均一性高的阻变存储器；采用分子动力学计算模拟阻变行为动力学过程并建立物理模型，利用动态蒙特卡洛方法成功模拟出金属导电细丝的形成与断开过程，揭示了导电细丝的形核位置与离子迁移率和形核激活能密切相关；探索了RedoxRRAM用于神经模拟相关原理，利用有机导电高分子异质结成功模拟神经突触可塑性，采用不同离子掺杂PEO和P3HT薄膜设计出有机人工突触器件，有效模拟了STP、STD等神经系统信号处理功能。基于上述研究与进展，构建出应用于十字交叉阵列的互补性阻变存储器和自整流效应阻变存储器，基于单个互补性阻变存储器实现了所有16种二元布尔逻辑运算。项目执行期间发表标注的SCI学术论文77篇，其中影响因子超过10的论文11篇，包括Materials Science & Engineering R: Reports 1篇（已单篇引用345次）、Progress in Materials Science 1篇、Nature Communications 1篇、Advanced Materials 3篇。科学出版社出版《阻变存储器材料与器件》专著一部。在国际会议作学术报告12次，其中邀请报告9次。