Multilevel switching mechanism for resistive random access memory based on Cu/SiOx/Al structure

In this paper, resistive switching device based on Cu/SiOx/Al structure is fabricated to examine its resistive switching characteristics and explore its resistive switching mechanisms. By adjusting limiting current, four stable resistance states are obtained. All of the resistive ratios between adjacent resistance states are over than 10. Moreover, the retention data of these four states at room temperature keep stable up to 1000 s. The temperature-dependent measurement and I-V curves fitting results show that the resistive switching mechanisms of the four states are different: resistance states 1 and 2 are due to Ohmic conduction mechanism, resistance state 3 is due to Pool-Frenkel emission, and resistance state 4 is due to Schottky emission mechanism. Subsequently, a resistive switching model for Cu/SiOx/Al structure is proposed.