Improved Resistive Switching Characteristics and Synaptic Functions of InZnO/SiO₂ Bilayer Device

This paper investigates the bipolar resistive switching and synaptic characteristics of IZO single-layer and IZO/SiO₂ bilayer two-terminal memory devices. The chemical properties and structure of the device with a SiO₂ layer are confirmed by x-ray photoemission spectroscopy (XPS) and transmission electron microscopy (TEM) imaging. The device with the SiO₂ layer showed better memory characteristics with a low current level, as well as better cell-to-cell and cycle-to-cycle uniformity. Moreover, the neuromorphic applications of the IZO/SiO₂ bilayer device are demonstrated by pulse response. Paired pulse facilitation, excitatory postsynaptic current, and pulse-width-dependent conductance changes are conducted by the coexistence of short- and long-term memory characteristics. Moreover, Hebbian rules are emulated to mimic biological synapse function. The result of potentiation, depression, spike-rate-dependent plasticity, and spike-time-dependent plasticity prove their favorable abilities for future applications in neuromorphic computing architecture.