“…However, silicon-based memory devices cannot easily meet the needs of the future development of data-storage devices owing to their physical and technological limitations, such as difficulty in fabrication processes, high fabrication cost, and high power consumption. ,− Resistive-switching memory (RSM) devices have emerged as next-generation memory devices owing to their simple structure, good scalability, and the wide variety of materials that may be used in their development. ,, RSM devices typically have two-terminal metal/insulator/metal structures . The characteristics of RSM can be optimized for high performance by designing low operating energy, fast operating speed, and high stability, depending on the materials of the insulating layer. − In addition, RSM devices can emulate synaptic functions through the use of analog resistive-switching characteristics. , The emulation of synaptic functions has emerged because they improve the performance of memory devices. − Synaptic functions are highly efficient computing processes in the brain that can handle complex computations with extremely low energy consumption, and they are emulated using memory devices called neuromorphic devices . Neuromorphic computing emulates synaptic plasticity, backpropagation learning, and synaptic-weight updates in the brain. − Changing the strength of connections between neurons, synaptic plasticity, and synaptic-weight updates are assumed to be mechanisms of memorization and computation in the brain. − Synaptic plasticity induces memory formation and information storage, whereas backpropagation learning enables the computation of the gradient of an objective function with respect to synaptic weight for parallel computing , …”