Anatomy of high-uniform unidirectional volatile switching behavior in SiO2/TiO2-based selection device

Unidirectional volatile switching behavior is a typical resistive switching phenomenon in oxides, which has been proposed as attractive candidates for selection devices for high density memory and neuromorphic systems applications with cross-point arrays. However, the microscopic origin of the underlying mechanism is still unclear due to the lack of direct experimental evidence. Here, a high performance selection device with a low forming voltage, low OFF-state current, high nonlinearity, and excellent uniformity is proposed in SiO2/TiO2 stacked structure. The underlying nature of the unidirectional volatile switching behavior in the Pt/Ag/SiO2/TiO2/Ti selection device is revealed by using scanning electron microscope and energy-dispersive X-ray spectroscopy analysis in planar structure devices, which can be attributed to the unstable conductive filament (CF) consisting of Ag nanoparticles formed in the SiO2 layer, and the Schottky contact formed between the Ag CF and TiO2 interface. This work provides clearly experimental evidence to deepen understanding of themechanism for unidirectional volatile switching behavior, which can provide a guide to further improve the device performances for high density memory and neuromorphic systems applications.