Low-power TiN/Al₂O₃/Pt resistive switching device with sub-20 A switching current and gradual resistance modulation

Resistive-switching random access memory (RRAM) using the TiN/AlO _x/Pt stack is fabricated with a 50 nm × 50 nm active area. The bipolar switching characteristic is observed using TiN as an anode and RESET current as low as sub-20 μA was achieved by using a current-limiting transistor as a selection device (1T1R) during the SET process. HRS to LRS ratio of 10³ for 10³ DC endurance test cycles is demonstrated. Switching time less than 10 ns was observed for both SET/RESET operations. By changing the gate bias of the series transistor and input voltage at the transistor drain terminal, multi-level resistance states can be modulated. Both the unipolar and bipolar resistance switching can coexist in such memory stacks and a qualitative model is proposed for the AlO_x-based RRAM resistive switching behavior.