Unipolar Nonvolatile Resistive Switching in Pt/MgO/Ta/Ru Structures Deposited by Magnetron Sputtering

The recent realization of memristors, nanodevices exhibiting non-volatile resistive switching, has sparked tremendous interest for applications in fields such as nonvolatile memories. Here we report unipolar resistive switching in Pt/MgO/Ta/Ru structures, with an oxide barrier thickness of only 15 nm. No electroforming process was required to achieve resistive switching and an ohmic conduction mechanism is associated with the ON state. We observed an inverse dependence of the ON state resistance on the SET current compliance and average values of 1.61 V and 1.38 V for the SET and RESET voltages, respectively. We show the stability of the switching for over 40 cycles and a clear separation of the ON (10¹ Ω) and OFF (10² Ω) states during at least 10⁴ s.