Rui Yang, Kazuya Terabe and colleagues at the National Institute for Materials Science (NIMS), and the International Center for Materials Nanoarchitectonics (MANA) in Japan and at the California NanoSystems Institute/UCLA havedeveloped “nanoionic” (processes connected with fast ion transport in all-solid-state nanoscale systems) devices capable of a broad range of neuromorphic and electrical functions.
Such a device would allow for fabrication of on-demand configurable circuits, analog memories, and digital-neural fused networks in a single device architecture. Synaptic devices that mimic the learning and memory processes in living organisms are attracting interest as an alternative to standard computing elements to help extend performance beyond current physical limits. However, artificial synaptic systems have been hampered by complex fabrication requirements and limitations in the learning and memory functions they mimic.
This device is based on a platinum-tungsten trioxide (WO3–x) device using oxygen ions migrating in response to voltage sweeps. Accumulation of the oxygen ions at the electrode leads to Schottky diode-like potential barriers and resulting changes in resistance and rectifying characteristics. The stable bipolar switching behavior at the platinum-tungsten trioxide-based device is attributed to the formation of a conductive filament and oxygen absorbability of the platinum electrode.
The researchers noted that the device properties* — volatile and non-volatile states and current fading following positive voltage pulses — are similar to neural behavior — that is, short- and long-term memory and forgetting processes. The device was found to possess a wide range of time scales of memorization, resistance switching, and rectification varying from volatile to permanent in a single device.