Interfacial redox processes in memristive devices based on valence change and electrochemical metallization
Interfacial redox processes in memristive devices based on valence change and electrochemical metallization
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基于价态变化和电化学金属化的忆阻器件中的界面氧化还原过程
DOI：
10.1039/c8fd00113h
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发表时间：
2018
影响因子：
3.4
通讯作者：
Ru Huang
中科院分区：
文献类型：
--
作者：
Ke Qin Liu;Liang Qin;Xiao Xian Zhang;Jiadi Zhu;Xinhao Sun;Ke Yang;Yimao Cai;Yuchao Yang;Ru Huang
基于电化学过程的忆阻器件是下一代存储器和神经形态应用的有希望的候选者。在界面处发生的氧化还原过程是电离以及产生反电荷的关键步骤，因此对于成功的电阻切换是必不可少的，但其详细机制尚未完全阐明。在这里，我们研究的界面氧化还原反应的形成过程中的忆阻器件的基础上价态变化和电化学金属化，使用高分辨率电子显微镜和静电力显微镜观察。我们显示直接的证据，氧离子的阳极氧化和阴极还原的水分在HfO2和Ta2O5为基础的价变化电池，这可能发生在不同的水平位置。我们进一步发现，阳极反应总是导致更明显的结构损伤的电极，表明额外的阴极反应，而不产生气体产物的可能性。当存在活性电极时，金属原子的氧化反而发生在阳极界面处。对电化学金属化电池的进一步研究发现，阳极反应和阴极反应分别是铜离子化和水分还原，并直接观察到阴极界面铜核的形成。这些微观证据的发现可以促进未来忆阻器件的发展。
Memristive devices based on electrochemical processes are promising candidates for next-generation memory and neuromorphic applications. The redox processes happening at the interfaces are crucial steps for the ionization as well as generation of counter charges, and are thus indispensable for successful resistive switching, but their detailed mechanism has not been fully clarified. Here, we study the interfacial redox reactions in the forming process of memristive devices based on valence change and electrochemical metallization, using high-resolution electron microscopy and electrostatic force microscopy observations. We show direct evidence for the anodic oxidation of oxygen ions and cathodic reduction of moisture in HfO2- and Ta2O5-based valence change cells, which could take place in different horizontal locations. We further found that the anodic reactions always led to more pronounced structural damage to the electrode, indicating the possibility of additional cathodic reactions without producing gaseous products. When an active electrode is present, oxidation of metal atoms takes place at the anodic interface instead. Further investigations on electrochemical metallization cells have identified Cu ionization and moisture reduction as the anodic and cathodic reactions, respectively, and formation of Cu nuclei at the cathodic interface was directly observed. These findings with microscopic evidence could facilitate future development of memristive devices.