Utilizing an SWCNT-TFT “Electronic Hourglass” for Artificial Synapse Application

“Electronic hourglass” refers to a type of metal-oxide-semiconductor (MOS) device that contains a large and time-dependent variable hysteresis. By positively considering the hysteretic behavior in MOS devices as an energy-storing phenomenon, information processing is available during the time-dependent shift of the device property. In this work, the “electronic hourglass” is extended to the area of neuromorphic application. By employing the highly electroactive carbazole group in polycarbazole (PCz), an “electronic hourglass” with a wide and reliable hysteresis has been successfully constructed using PCz-sorted single-walled carbon nanotube thin-film transistors (SWCNT-TFTs). By focusing on the similarities between the “electronic hourglass” that features a shift of threshold voltage (VT) and a biological synapse, an artificial synapse with typical paired-pulse facilitation (PPF) and spike-timing dependent plasticity is realized. Moreover, the metaplasticity of the PCz-sorted SWCNT-TFT could modulate plasticity by shifting the number and amplitude of the prime spikes. In this way, the modulation of the synaptic weight (resistance) and a transformation from PPF to paired-pulse depression can be achieved. Finally, the imitation of the Pavlovian conditioned reflex experiment is demonstrated.