Publication Date

December 2010

Journal or Book Title

Applied Physics Letters


We demonstrate over 11010 open-loop switching cyclesfrom a simple memristive device stack ofPt/TaOx /Ta. We compare this system to a similar devicestack based on titanium oxides to obtain insight into thesolid-state thermodynamic and kinetic factors that influenceendurance in metal-oxide memristors.Memristive devices have attracted significant attentionbecause of their great potential for next generationnonvolatile memory,1,2 stateful logic operations via materialimplication,3 neuromorphic computing,4 and a variety ofcomplementary metal-oxide semiconductor CMOS/memristor hybrid circuits.5,6 Accordingly, significantprogress has been made in understanding the physicaloperating mechanisms as well as in improving thedevice performance,7–22 leading to the demonstrationof nonvolatility, fast switching 10 ns, low energy1 pJ/ operation, multiple-state operation, scalability,stackability, and CMOS compatibility for these devices.However, one of the major challenges for memristors to beused in a universal memory e.g., replacing DRAM as wellas Flash or as a Boolean computing device is endurance,1,7i.e., how many cycles the devices can reversibly and reliablyswitch. The endurance values reported in the literature rangefrom 10 to 1106 cycles and the endurance record has been1109 cycles so far.19 Here we demonstrate that the endurancelimit of metal-oxide memristive devices has not yetbeen reached. We have achieved over 11010 switchingcycles see Fig. 1a in a very simple Pt/TaOx /Ta devicestack while using fixed switching parameters in an open circuitwithout any feedback mechanism. The device remainsfunctional even after 15109 cycles. We have comparedTiOx- and TaOx-based memristors with a similar devicestructure and observed a significantly better endurance in thelatter. Based on these observations and the known phase diagramsfor the Ti–O and Ta–O systems, we discuss some criteriafor material selection to achieve high endurance.