The Conduction Mechanism And Radiation Tolerance Against TID Effect Of TiO₂-based Resistive Switching Device

With the advancement of scaling technology, the currrent mainstream non-volatile memory(NVM) technology based on charge storage, such as flash memory, is suffering from low endurance, low access speed, and high operation voltage, and will reach its scaling limit in the near future due to decreasing feature sizes. In order to overcome the problems of current NVM technologies, several emerging storage concepts have been explored and attracted considerable attention. Among them, the resistive random access memory(RRAM) based on resistive switching devices is considered as one of the most promising candidate, due to the potential of fast access speed, low power consumption, simple fabrication process, especially high integration and multilevel data storage ability. In addition, the resisitive switching devices can also be used in reconfigurable logic circuits and neuromorphic system. However, the device performance cannot meet the requirement of practical application, which has been a major issue and challenge for the research of resistive switching devices. Furthermore, the underlying physical mechanisms are still controversial, and should be further addressed.In this paper, we fabricate resistive switching devices of Au/TiO2/Au with the crossbar structure. The resistive switching characteristics are investigated. By performing the fitting of the I-V curve, we analyze the conduction mechanisms in high resistance state and low resistance state, respectively. We propose a physical model by combining the electron tunneling and the interface barrier height modulated by the motion of oxygen vacancies.By controlling the compliance current, the mulitilevel storage can be achieved. The degradation of multilevel storage is observed, which could be attributed to the variation in oxygen-vacancy and ion densities with respect to the switching cycles. For the stage-like resistive switching effect, we establish a physical model of the formation and rupture of multi-filaments.The total ionizing dose effect is experimentally investigated on the resistive switching devices. After the γ-ray irradiation, the device parameters including the resistances and the switch voltages degrades, but the uniformity of the I-V curve is improved. The degradations have no impact on the data storage, indicating the great radiation tolerance of the resistive switching devices.