Resistive Random Access Memory Cells with a Bilayer TiO2/SiOX Insulating Stack for Simultaneous Filamentary and Distributed Resistive Switching

In order to fulfill the information storage needs of modern societies, the performance of electronic nonvolatile memories (NVMs) should be continuously improved. In the past few years, resistive random access memories (RRAM) have raised as one of the most promising technologies for future information storage due to their excellent performance and easy fabrication. In this work, a novel strategy is presented to further extend the performance of RRAMs. By using only cheap and industry friendly materials (Ti, TiO2, SiOX, and n(++)Si), memory cells are developed that show both filamentary and distributed resistive switching simultaneously (i.e., in the same I-V curve). The devices exhibit unprecedented hysteretic I-V characteristics, high current on/off ratios up to approximate to 5 orders of magnitude, ultra low currents in high resistive state and low resistive state (100 pA and 125 nA at -0.1 V, respectively), sharp switching transitions, good cycle-to-cycle endurance (> 1000 cycles), and low device-to-device variability. We are not aware of any other resistive switching memory exhibiting such characteristics, which may open the door for the development of advanced NVMs combining the advantages of filamentary and distributed resistive switching mechanisms.