Search

Resistive-switching random access memory (RRAM) devices utilizing a crossbar architecture represent a promising alternative for Flash replacement in high-density data storage applications. However, RRAM crossbar arrays require the adoption of diodelike select devices with high on–off -current ratio and with sufficient endurance. To avoid the use of select devices, one should develop passive arrays where the nonlinear characteristic of the RRAM device itself provides self-selection during read and write. This paper discusses the complementary switching (CS) in hafnium oxide RRAM, where the logic bit can be encoded in two high-resistance levels, thus being immune from leakage currents and related sneak-through effects in the crossbar array. The CS physical mechanism is described through simulation results by an ion-migration model for bipolar switching. Results from pulsed-regime characterization are shown, demonstrating that CS can be operated at least in the 10-ns time scale. The minimization of the reset current is finally discussed. [ABSTRACT FROM AUTHOR]

Understanding the physical mechanisms for resistance change in metal oxides is a key challenge to assess the scalability of resistive-switching random access memory (RRAM) devices. From this standpoint, the time dependence of filament formation and dissolution in metal oxides can provide a useful insight into the fundamental mechanism of resistive switching. In this paper, we show an experimental study of the time-dependent filament growth and of the voltage dependence of set/reset times in \HfOx-based RRAM devices. The voltage across the device is shown to be regulated at any given time irrespective of the compliance current and the applied voltage, evidencing that voltage is the controlling parameter for the filament formation and dissolution during switching. These results are explained in terms of a thermally-activated ion migration model for filamentary switching. The model allows for an analytical calculation of the scaling dependence of set/reset times and energies in RRAM. [ABSTRACT FROM AUTHOR]

Set and reset characteristics are studied for unipolar and bipolar metal-oxide resistive-switching memory devices. We show a universal dependence of set-state resistance and reset current on the compliance current used during set, with negligible impact of metal-oxide composition and switching condition. An analytical Joule-heating model for universal reset is presented, predicting a weak dependence of reset temperature and voltage on diffusion and migration parameters in both unipolar- and bipolar-switching modes. Data for the reset voltage are shown for a wide range of unipolar and bipolar metal oxides, in support of our calculations. [ABSTRACT FROM AUTHOR]

Resistive-switching memory (RRAM) devices are attracting a considerable interest in view of their back-end integration, fast programming, and high scalability. Prediction the programming voltages and currents as a function of the operating conditions is an essential task for developing compact and numerical models able to handle a large number (106-109) of cells within an array. Based on recent experimental findings on the set and reset processes, we have developed physics-based analytical models for the set and reset operations in NiO-based RRAMs. Simulation results obtained by the analytical models were compared with experimental data for variable pulse conditions and were found consistent with data. The set transition is described by a threshold switching process at the broken conductive filament (CF), while the reset transition is viewed as a thermally driven dissolution and/or oxidation of the CF. Set and reset models are finally used for reliability predictions of failure times under constant-voltage stress (read disturb) and elevated-temperature bake (data retention). [ABSTRACT FROM AUTHOR]