Conduction channel configuration controlled digital and analog response in TiO2-based inorganic memristive artificial synapses

The operating current regime is found to play a key role in determining the synaptic characteristic of memristor devices. A conduction channel that is formed using high current compliance prior to the synaptic operation results in digital behavior; the high current stimulus forms a complete conductive filament connecting the cathode and anode, and the high electric field promotes abrupt redox reactions during potentiation and depression pulsing schemes. Conversely, the conduction can be reconfigured to produce a filamentary-homogeneous hybrid channel by utilizing the low current stimulus, and this configuration enables the occurrence of analog behavior. The capabilities of memristors showing programmable digital-to-analog or analog-to-digital transformation open a wide range of applications in electronics. We propose a conduction mechanism to explain this phenomenon.