Research colloquium neuromorphic electronics
Peter Grünberg Institute and JARA-FIT, Forschungszentrum Juelich GmbH, Juelich, Germany
Transition metal oxides exhibit a reversible, non-volatile change in electrical resistance upon electrical stimulus, a phenomenon known as resistive switching. In the simplest case resistive switching memory cells, or so called memristive devices, can be switched between a low resistance state (LRS) and a high resistance states (HRS) which can be interpreted as the logical "1" and "0", respectively. However, it is important to note that resistive switching cells often show multiple resistive states rather than only two logical states and can therefore be used for multibit memory or implemented as synapses in neuromorphic circuits.
Based on the current knowledge, resistive switching in memristive elements based on transition metal oxides can be ascribed to electrically induced redox-processes at the oxide/electrode interface, which occur either in a spatially confined switching filament, multiple filaments or in a spatially homogeneous, area-dependent manner.
The recent status of understanding of switching and failure mechanisms of redox-based memristive devices gained from spectromicroscopic studies will be presented. We will discuss how the spatial extension of the redox-processes and the ion mobility of the oxide interface layers impact the switching kinetics and the reliability of the devices. Based on this, we will discuss challenges and strategies to gain control over the performance and reliability of the devices which will be crucial for their use in future neuromorphic circuits.