Memory-State Dependence of Random Telegraph Noise of hbox Ta 2 hbox O 5 / hbox TiO 2 Stack ReRAM

Memory-state [low-resistance state ( R L ) and high-resistance state ( R H ) ] dependence of random telegraph noise (RTN) of hbox Ta 2 hbox O 5 / hbox TiO 2 resistive random access memory is investigated. The conduction mechanism of both memory states and a limit of resistance controllability are also investigated to clarify the difference in the RTN mechanism of both states. The boundary between the R L and R H states was found at 5-20 hbox k , and the conduction mechanism much depended on the memory state. The noise also depended on the memory state. The noise amplitude in the R H state was larger than that in the R L state. In the R H state, a tunnel barrier was generated to cut off a conduction path (filament), and traps inside the tunnel barrier were supposed to increase the noise amplitude. Moreover, the composition of the following degraded the noise distribution in the R H state: 1) capture and emission of charges with traps and 2) instability of these traps against the bias temperature stress.