This review addresses resistive switching devices operating according to the bipolar valence change mechanism (VCM), which has become a major trend in electronic materials and devices over the last decade due to its high potential for non-volatile memories and future neuromorphic computing. We will provide detailed insights into the status of understanding of these devices as a fundament for their use in the different fields of application. The review covers the microscopic physics of memristive states and the switching kinetics of VCM devices. It is shown that the switching of all variants of VCM cells relies on the movement of mobile donor ions, which are typically oxygen vacancies or cation interstitials. VCM cells consist of three parts: an electronically active electrode (AE), often a metal with a high work function, in front of which the switching occurs, a mixed ionic-electronic conducting (MIEC) layer consisting of a nanometer-scale metal oxide or a stack of different metal oxides, and an ohmic counter electrode (OE). After an introduction to definitions and classification, the fundamentals of solid-state physics and chemistry associated with VCM cells are described, including redox processes and the role of electrodes. The microscopic changes induced by electroforming, a process often required prior to resistive switching, are described in terms of electronic initialization and subsequent changes in chemistry, structure, and conductivity. The switching process is discussed in terms of switching polarity, geometry of the switching region, and spectroscopic detection of the valence changes. Emphasis is placed on the extreme nonlinearity of switching kinetics described by physics-based multiscale modeling, ranging from ab initio methods to kinetic Monte Carlo and finite element models to compact models that can be used in circuit simulators. The review concludes with a treatment of the highly relevant reliability issues and a description of the failure mechanisms, including mutual trade-offs.

这篇综述讨论了根据双极化合价变化机制 (VCM) 工作的电阻开关器件，由于其在非易失性存储器和未来神经形态计算方面的巨大潜力，它已成为过去十年电子材料和器件的主要趋势。我们将提供对这些设备的理解状态的详细见解，作为它们在不同应用领域中使用的基础。这篇综述涵盖了忆阻态的微观物理学和 VCM 器件的开关动力学。结果表明，VCM 细胞的所有变体的切换依赖于移动供体离子的移动，这些供体离子通常是氧空位或阳离子间隙。VCM 电池由三部分组成：电子活性电极 (AE)，通常是具有高功函数的金属，在切换发生之前，由纳米级金属氧化物或不同金属氧化物的堆叠组成的混合离子电子导电 (MIEC) 层和欧姆对电极 (OE)。在介绍了定义和分类之后，描述了与 VCM 电池相关的固态物理和化学的基础知识，包括氧化还原过程和电极的作用。电铸引起的微观变化是电阻转换之前经常需要的一个过程，用电子初始化和随后的化学、结构和电导率变化来描述。切换过程在切换极性、切换区域的几何形状和价态变化的光谱检测方面进行了讨论。重点放在基于物理的多尺度建模所描述的开关动力学的极端非线性上，范围从从头算方法到动力学蒙特卡罗和有限元模型，再到可用于电路模拟器的紧凑模型。审查以对高度相关的可靠性问题的处理和对故障机制的描述（包括相互权衡）结束。