In this paper, we report multi-level cell (MLC) switching characteristics of resistive random access memory devices with a W/Zr/HfO 2 /TiN stack. A multi-step forming technique was implemented in this work which efficiently suppressed the forming current overshoot and allowed device switching at a low set/reset voltage and current. Four distinct resistance states, achieved by controlling the reset stop voltages, showed excellent endurance. Write/read/erase energy values for different states were also calculated. Amongst four MLC states, it was found that the lowest resistance state of three distinct high-resistance states was prone to failing over time under constant voltage stress.
We report the switching dynamics and charge transport studies on Ru/HfO2/TiOx/Ru resistive random access memory devices in low resistance state (LRS), high resistance state (HRS), and virgin resistance state (VRS). The charge transport in LRS is governed by Ohmic conduction of electrons through local filamentary paths while it is governed by a combination of Frenkel-Poole emission and trap assisted tunneling process in HRS and VRS. The area of the filament in LRS is extracted and related to the compliance current. The thickness of the re-oxidized filament is extracted and related to the reset voltage in HRS. The energy consumed during the reset process was analyzed on the time-scale to experimentally demonstrate joule-heating mediated oxidation dynamics of filament during device reset.
We report the synaptic characteristics of novel two-terminal reconfigurable devices fabricated using a doped transition metal oxide. These devices demonstrate short-term plasticity, frequency-dependent synaptic augmentation, long-term potentiation, and long-term depression, and have a potential to show spike timing-dependent plasticity that are macroscopically similar to a biological synapse. The underlying mechanism behind the observed synaptic characteristics was studied using charge transport characterization. Based on this study, a fundamental correlation between the governing device physics and the synaptic characteristic has been established. We believe that by carefully engineering the dopants, the synaptic transmission of these devices can be modulated, which will provide a viable route to replicate the functional diversity of a biological neural system on chip.Index Terms-Memristive device, plasticity, synapse, transition metal oxide.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.